The doctrine decimal arithmetick, simple interest, &c. as also of compound interest and annuities generally performed for any time of payment or rate of interest by help of a particular table of forbearance of 1l principal, with enlarged rules, formerly abridged for portability in a letter case / by John Collins ; and since his death, both made publick by J.D. Collins, John, 1625-1683. 1685 Approx. 107 KB of XML-encoded text transcribed from 55 1-bit group-IV TIFF page images. Text Creation Partnership, Ann Arbor, MI ; Oxford (UK) : 2005-12 (EEBO-TCP Phase 1). A33998 Wing C5372 ESTC R23930 07929253 ocm 07929253 40487 This keyboarded and encoded edition of the work described above is co-owned by the institutions providing financial support to the Early English Books Online Text Creation Partnership. This Phase I text is available for reuse, according to the terms of Creative Commons 0 1.0 Universal . The text can be copied, modified, distributed and performed, even for commercial purposes, all without asking permission. Early English books online. (EEBO-TCP ; phase 1, no. A33998) Transcribed from: (Early English Books Online ; image set 40487) Images scanned from microfilm: (Early English books, 1641-1700 ; 1203:2) The doctrine decimal arithmetick, simple interest, &c. as also of compound interest and annuities generally performed for any time of payment or rate of interest by help of a particular table of forbearance of 1l principal, with enlarged rules, formerly abridged for portability in a letter case / by John Collins ; and since his death, both made publick by J.D. Collins, John, 1625-1683. [5], 102, [1] p. Printed by R. Holt for Nath. Ponder, London : 1685. Note in manuscript: p. [103] Reproduction of original in the Cambridge University Library. Created by converting TCP files to TEI P5 using tcp2tei.xsl, TEI @ Oxford. 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Decimal system. 2005-07 TCP Assigned for keying and markup 2005-08 Apex CoVantage Keyed and coded from ProQuest page images 2005-09 John Latta Sampled and proofread 2005-09 John Latta Text and markup reviewed and edited 2005-10 pfs Batch review (QC) and XML conversion The Doctrine of DECIMAL ARITHMETICK , Simple Interest , &c. AS ALSO Of Compound Interest AND ANNUITIES ; Generally performed for any time of Payment , or Rate of Interest , by help of a particular Table of Forbearance of 1 l. Principal , with Inlarged Rules . Formerly abridged for portability in a Letter Case . By John Collins Accomptant , Philomath . And since his Death both made Publick by J. D. LONDON , Printed by R. Holt for Nath. Ponder at the Peacock in the Poultry , near the Stocks-Market , 1685. THE EPISTLE TO THE READER . Courteous Reader , IT is the accustomed way to Dedicate Books to some Honourable Person , that thereby the Book might have the greater Esteem . This Book needs no such Dedication , for the Name of the Author ( which will never dye , Ingenious Mr. John ted at the end of the Book , whereby the Reader may see it no ways derogates from the Old Copy , and thereby may see how full and plain the New Rules are in comparison to the Old. This Book is a fit Companion for all Gentlemen , Merchants , Scriveners , and other Trades-men , that deal much in lending of Money upon Interest , Mortgages , buying of Estates either in Fee , Copy , or Lease , holding Annuities , Rent Charges , Forbearance of Money , Discompt , or any other way concerning Interest , &c. When any Person does perfectly understand the large Rules , he may if he pleases lay by the Book , and only use the Compendium with the Tables to be carried about in a Letter Case ; and I hope in perusing this small Treatise the Reader will find that which will give him Satisfaction , both as to the Rules and Tables . Yours , J. D. Decimal Arithmetick . A Decimal Fraction is such a one whose Denominator is understood , and not expressed ; and is an Unit with as many Cyphers following it , as there are Figures and Cyphers in the Numerator . Corollary , Wherefore the annexing of Cyphers towards the right hand of a Decimal , alters not its value . A Decimal Fraction of Coin may be easily valued without the help of Tables . For each Unit in the first place is in value 2 s. 5 in the second place 1 s. and the rest Farthings ; but if they exceed 25 / 48 there must be two farthings abated . Example . So ,854 is in value 17 s. 1 d. ,418 8. 4½ Addition and Substraction in Decimals is the same , as in whole Numbers , keeping the place of Units just under each other . Multiplication in Decimals is the same , as in Common Arithmetick , saving as many Decimal Parts as are in both Multipliers , so many must be cut off from the Product , which if it have not so many places , the Defect is to be supplied with Cyphers towards the left hand . Division is the same as in whole Numbers , without regard to Decimals till the Work is done , and then use the Converse of the Rule for Multiplication ( viz. ) so many Decimals as are in the Dividend , so many there must be in the Divisor and Quote , and if there be not so many , the Quotient must be supplied with Cyphers towards the left hand . Simple Interest . PROP. 1. TO compute the Interest for a day , 6 / 365 is the Interest of 100 l. for a Day the 1 / 100 , whereof is the Interest of 1 l. for a Day ( viz. ) 6 / 36500 ; Or 6 ( with Cyphers put on at pleasure ) divided by 36500 is , 000164383 the Interest of 1 l. for a Day . Prop. 2. The Decimals of Days in the Table at the end will serve to find the amount of 1 l. Simple Interest of any Rate for any time under 365 Days or a Year . If you take the Decimal for one day ( or more ) and multiply that by , 06. 7. 8. &c. per Cent. or any other Rate , the Product will give the Interest of one pound for a Day , or more under 366 Days at Simple Interest . Example 1. The Decimal for a day is ,002739726     ,06 The Interest of 1 l. for a day ,00016438356 Example 2. The Decimal of 121 days is ,331506849   ,06 The Interest of 1 l. for 121 days ,01989041094 ,002739726 Decimal for a day ,07 per Cent. ,00019178082 The Interest of 1 l. for a day at 7 l. per Cent. And so of any other rate of Interest . Prop. 2. Forbearance of Money at Simple Interest . The Interest of 1 l. for any Number of days , at what rate of Interest you please , be first found by the first Proposition , that Product multiplied by the Sum propounded , gives the Interest thereof for the time required . Example . To know the Amount of 140 l. for 121 days , at 6 l. per Cent. Simple Interest . The Decimal of 1 l. for 121 days 1,019890410 Multiplied by 140 Which is 142 l. 15 s. 8 d. 40795616400   1,019890410   142,784657400 Prop. 3. Rebate , or the Present worth of Money due hereafter . Find the Interest of 1 l. for the time given , as in Prop. 1. And thereto add an Unit by it . Divide any other Sum propounded , and the Quote is its present Worth. Example . If 142 l. 15 s. 8 d. be due at the end of 121 days , what is it worth in ready Money ? Worth in ready Money 140 l. at 6 l. per Cent. Simple Interest , and may be done for any other rate of Interest , working by the first Proportion and this former Rule . Prop. 4. Equation of Payments . By Prop. 3. compute all the Present Worths , and then by Proportion . If all those Present Worths amounted to the Total of all those Payments , what did one pound amount to in the said time ? From the result substract an Unit , the Remainder is the Interest of 1 l. for the time sought , which divide by the Interest of 1 l. for a day , the Quote is the Number of days sought . If you are to Aequate an Annuity , at Simple Interest . I presume a Compendium may be found in Mengolus his Arithmetical Quadratures ( a Book I never saw ) who it 's probable by a Compendium gets the fact of an Arithmetical Progression , and adds Fractions that have a constant Numerator , and an Arithmetical Progression for their Denominators . So much for Simple Interest , my Design being more for the Explanation of the Tables for Compound Interest and Annuities . Of Compound Interest . THe Original thereof is Derived from Simple Interest , for if it be Lawful to take Interest at all , then it is as Lawful to put out the Interest-Money to Use , as the Principal . For ease in Calculating Questions that concern Compound Interest , Arithmeticians do usually frame Tables in store , to shew what 1 l. Principal forborn at any Rate for any determinate time shall amount unto ; the Construction whereof is by the Golden Rule , as followeth ; As 100 l. Principal is to the amount thereof at the years end ; So is an Unit. To its amount ( to wit. ) So is 1. 1 , 06. If 6 be the rate of Interest , then it will hold again for the next year . As 1. 1 , 06 , so 1 , 06 , to 1 , 1236 , the principal and Interest at the second year . Now because an Unit is in the first place , which doth not divide , it followeth , that the second years amount Squares the Number 1 , 06 , being the Quotient of 1 , 06 divided by 100 , and that is the amount of 1 l. forborn a year , the Compound Interest the third year Cubes it , &c. And the said Number 1 , 06 is by Arithmeticians called the Ratio , Quote or Denominator of the Ratio propounded , and the Logarythm thereof multiplied by the time doth raise those Powers agreeable to the nature of Logarythms . By the former Proportion was the following Table for years made , or for Abridgment by Addition , only by help of a Table of 1,06 multiplied by all the Digits ; And this raising of Powers is by some called Involution , and as for that of Months may be made by finding mean Proportionals , and those of days by help of the Common Logarythms , or without , supplied far enough downward , by help of mean Proportionals , and a Decimal Table for time , and three Months here is understood to be the precise ¼ of a whole year , and so of the rest . That which we add concerning it , is , That it self is in effect no other than a Table of Logarythms , but of another kind than those in Print , yet herein agreeing therewith , that in both the Logarythm of an Unit is O , and therefore this Table may be continued for any large time by one or some few Multiplications , it is here continued to each year for 50 years , then for every 10 years to 100 , whereby you may perceive that an Inheritance , or a Sum due after such a time is worth little more than a three hundred and fortieth part of its present Worth. And in the next place it will supply the Defect of all other Tables ( especially those that relate to the said rate of Interest ) whether of Discount of Money or of Forbearance of and Discount of Annuities , or for the Purchase thereof . In the Tables following the number of years are the Logarythms or Indexes , and the Amounts are the Numbers to which the Logary thms belong , and because this is no full Table of Logarythms to ten or one hundred thousand , we therefore use Multiplication and Division to supply those Defects , wherefore the first Prop. is ; Prop. 1. To continue the said Table . Multiply the Numbers together that belong to any Numbers of years , that added together make the years of Continuance required . Example . Let it be required to find the Amount of 1 l. for 50 years . 20 Years   3,20713 30 Years   5,74349 50 Years Product is 18,42015 and is the Number sought , omitting the five superfluous places of Decimals . Another Example . It is required to find the Amount of 1 l. forborn 20 years three quarters . 20 Years is 3,20713 9 Months 1,04467 The Product 3,25180 And the like may be done for days , and the Converse when an Amount is given , the time thereto may be found by Division , searching in the Table what Number amongst the Decimals for time agrees to the Divisors and last Quote . See Prop. 8. the First Section . And here it is worth noting , That many Questions may be put concerning Compound Interest , which are of the like difficulty , as to raise the printed Logarythmetical Cannon . For Example such a Question may be put ; One pound was put out at Compound Interest , and in 10 years time amounted to 10 l. in what space of time did it amount to 2 l. the answer is the Logarythm of the Number two ( to wit ) 3,01023 years which was not raised without much toyl , and the rate of Interest in those Logarythms is near 26 l. per Cent. to wit 25,89292 . The Uses of the said Table . Prop. 2. A Sum forborn for any time , to find to what it shall amount to at 6 l. per Cent. Compound Interest . Find in the Table , or Compute by 1. Prop. the amount of 1 l. for the said Time , and then it holds . As 1 l. is to its Amount ; So any other Sum to its Amounts : Wherefore the Amount of 1 l. must be multiplyed by the Sum proposed . Example . What shall 136 l. 15 s. 06 d. amount unto being forborn 20 years at 6 per Centum ? The Amount of 1 l. for 3,20713 20 years is Which multiplied by 136,775 The Product is 438,655 Reduced is 438 l. 13 s. 1 d. 4● Prop. 3. A Sum of Money due hereafter , to find what it is worth in ready Money . Find in the Table what 1 l. forborn , the like time shall amount unto at Compound Interest , then it holds . As the said Amount is to an Unit ; So is any Sum propounded , to its present Worth. Corollary . Therefore if an Unit be the Sum whereof you would find the present Worth , you will frame the Numbers in the usual Table for Discount , and for all other Sums : Because an Unit doth not Multiply , it will follow they must be divided by the Amount of 1 l. for the like time . Discount , or the present Worth of Money due hereafter . Example first , for making the Table of Discount . An Unit divided by 3,20713 , the Quotient is 311804 , the present Worth of 1 l due 20 years hence . Example second . If 400 l. be due 20 years hence , What is it worth in ready Money , abating Compound Interest at 6 per Centum per Annum ? Divide 400 by 3,20713 , the Amount of 1 l. forborn 20 years at Compound Interest , and the Quotient is 124 l. 722 , or 124 l. 14 s. 5 d. ¼ And how to reduce sundry Payments , to an Equation of time at Compound Interest . See first Example of Prop. 8. Prop. 4. Of Forbearance of Annuities . To find the Arrearages of an Annuity . The Difference between the Forbearance of an Annuity , and of a Principal put out to Interest , is this , that every year there is a Principal like the first added . The Proportion holds . As , 06 the Compound Interest of 1. l. for a year , is to the Amount less by an Unit of one of one pound forborn at Compound Interest for the time proposed . So is any Annuity or yearly payment of Rent forborn the like time , and at the same Rate , to the Arrearages thereof due . And when the Rent is payable Half-yearly , Quarterly , the first term in the proportion must be the Compound Interest of 1 l. for acordingly , &c. Half a year , Quarter , Example . Let it be required to find what one pound a year Annuity forborn for 30 years at 6 per Centum shall amount to . One pound forborn at Compound Interest so long amounts to 5 , 74349 which lessened by an Unit is 4 , 74349 which divided by 06 , the Quotient is 79 , 0581 and this is the Number found in the Vulgar Tables for forbearance of Annuities . Second Example . Let it be required to find what 20 l. Annuity forborn for 15 years shall amount unto at 6 per Centum . 1 l. Principal forborn 15 years amounts to 2 , 39655 from which subtracting an Unite it holds . As , 06 to 1,39655 so 20 to 465 , 516 , that is 475 l. 10 s. 4 d. Third Example . A Quarterly Rent of 25 l. was respited 20¾ years , by the first Proportion the amount of 1 l. so long forborn was 3 , 34978. And the Interest of one pound for a quarter is 0 , 14675 Wherefore by Proportion , As , 014675 Is to 2 , 34978 : So is 25 to 4003 , 032 that is 4003 l. 00 s. 7¾ d. This Useful Proportion I thus demonstrate which the Reader may pass by . Imagine the Land or Stock that yields an Annuity to be such a Principal sent out for the whole term as will bring in so much yearly Interest as the Annuity comes to , then at last the whole at Compound Interest is to be repaid , whereof so much is supposed to be repaid in the Value of the Land , as its first Principal came to , and the rest in Money ; wherefore out of the whole Amount of that Principal and its Interest , the Principal must be deducted unless to shun it by that which Geometers call conversion . See Commentators on 16 Def. Quinti Euclidis &c. we say , As the first term is to the difference of the first and second ; So the Third Term to the difference of the third and fourth . The Plain Proportion grounded upon the former Considerations runs thus , As 1 l. Principal . Is to its Amount for the time forborn ; So the Principal that shall bring in any Annuity proposed . To the Sum of the said Principal and of the Arrearages of the Annuity . Then it will hold by conversion of Reason . As 1 l. forborn at Compound Interest is to its Amount less by an Unit for the time forborn ; So is the Principal of an Annuity , forborn the like time , To the Arrearages of the Annuity . And instead of the third term of this Proportion , we may take in a fraction equivalent thereto , the Numerator whereof is the Annuity or yearly payment of Rent , and the Denominator the Interest of 1 l. for a year ; for to find the Principal of an Annuity say , As 6 is to 100. Or rather , 06 : 1. So is the Annuity to its Principal . And both these latter Proportions compounded into one will be the proportion first delivered , the Units in each being expunged as insignificant either in Multiplication or Division . Prop. 5. To find the present worth of an Annuity . If an Annuity be forborn till the last payment be due , then for as much as the Interest of each particular payment is by the former or 4th . Proposition computed , if by the 3d. Proportion the same , together with the rebate of each payment be destroyed ( to wit ) the present worth of the whole Arrearage be computed it shall be the present worth of the Annuity , the Proportion in both those Propositions being after the manner of the 4th . prop. composed into one it will hold for Annual payments at 6 per Centum . As the fact of ( ,06 ) the Interest of 1 l. for a year , and of the Amount of one pound Compound Interest for the time proposed , is to the said Amount less an Unit. So is the Annuity or yearly Rent to the present worth thereof . Example . First for making the Tables . To find the present worth of an Annuity of 1 l. per Annum , to continue 25 years at 6 per Centum compound Interest . The Amount of 1 l. for that time is 4,29187 which Multiplyed by ,06 the fact is ,257512 , whereby dividing 3,29187 the Quote is 12 l. ,78335 the present worth sought . Example . Secondly for half-yearly Payments . An Annuity of 40 l. payable , 20 l. each half year is to befold for 12 years at 6 per Centum . The Compound Interst of 1 l. for half a year is — ,029564 The amount of 1 l. forborn 12 years — 2,012196 Multiply these two together , and that added together makes the fact of both ; Which is — ,058487 It therefore holds , As ,058487 is to ,1,012196 . So is 20 to 346 , 166 that is 346 l. 3 s. 4 d. the present worth thereof . If this Annuity were paid yearly it must be of less Value because the mony is longer in coming in , and accordingly the worth of it l. s. d. would be but — 335 — 7 — 1 Admit it were required to know what an addition of 8 years more is worth after 12 are expired .   The worth of the said Annuity for 20 years , is — 458. 15. 11 The difference of these two is — being the present worth of the 8 years sought . 123. 8. 10 Prop. 6. To find what Annuity any Sum of ready Money shall purchase . This is but the Converse of the former Proposition , and it holds therefore ; As the Amount of 1 l. forborn at Compound Interest less an Unit is to the fact of , 06 and of the Amount of one pound so forborn , So is any Sum of ready mony to the Annuity it shall purchase . In this and the two former propositions by ,06 is understood the Compound Interest of 1 l. for a year , and when the payment is by quarters or half years , instead thereof must be put in the Interest of a quarter or half a year . And instead of the Annuity or yearly payment , the Quarterly or Half-yearly payment accordingly . Corollary . If 1 l. be the sum of ready mony then the two middle Terms of the proportion are the fact above mentioned , and you will frame the other Vulgar Table for this purpose . Example the first . To find what Annuity 1 l. shall purchase to continue 30 years , it holds ; As 4,74349 to ,06 . So 5,74349 to 0,07264 . Example Second . Let it be required to find what rent payable yearly 8 l. shall purchase at 6 per Centum to continue 21 years . As 2,39956 the Amount less an Unit of 1 l. for 21 years is to ,20397 the fact of ,06 and the amount , So is 8 to ,68 or 13 s. 7¼ d. the Annuity sought . Memorandum , That by the Fact is meant that you should multiply the foregoing Figures by ,06 . Viz. 2,39956 by ,06 , Which makes 2,2039736 . Now whereas the Lease of a house of 1 l. per Annum to continue 21 years is commonly sold for 8 l. or 8 years purchase , and your mony will purchase a certainty but of 13 s. 7 d. ● per Annum , you see by this supposition you are abated 6 s. 5 d. 3 / ●nt of Taxes Reparations and Casualties ; and verygood Reason there is for great abatements , for a Tenant taking a Lease on a Tunber house , if it be burnt down by a Fire beginning at his Neighbours as leases commonly Run , is bound to build it up again and hath no relief either in Law or Equity against his Landlord , as I am informed by able Council , only he hath the benefit of a Benevolence , his Action against them where the fire began ( who perchance are ruined . ) s.   s. d.   will purchase an — 11 — 11 10 Annuity to continue 21 years of — 12 — 9 10   — 14 — 5½     — 15     — 17     1 — 5 — 3½ — 1-00-0 Hence it appears that the Value of Leases of Houses cannot be estimated near the Truth by the Common Tables for Annuities at the currant rate of Interest , and that if any one would use them to this purpose it were much nearer the truth first to abridge the Rent as aforesaid . Prop. 7. Any number of years in a Lease or Annuity being propounded to find the present Worth of any greater or lesser Number of years therein . This is one of the most usual and useful Propositions of this Nature , and as propounded is not sufficiently Limited , and the Question in this Cas● will be , What is the most equitable rate of Interest whereby to resolve the Proposition ; to find out which it is either necessary to assign how many years purchase the Fee Simple or Inheritance is worth , or the present Worth of a Lease of any Number of years therein . 1. If the Worth of the Inheritance be assigned , then thereby divide 100 the Quote shews the Annual Interest for . Example : Let the Fee Simple or Copy-hold Lands be worth 16 years 8 months Purchase , then dividing 100 by 16⅔ the Quotient is 6 , whereof 6 pound in the 100 is an equitable Rate of Interest whereby to compute the present worth of a Lease of any number of years therein , and so è contra if mony were at 8 per Centum , the Laws of Arithmetick allow the worth of the Inheritance of the best Land that is , to be but 12½ years Purchase , which some would confirm , from this reason , because otherwise their money would yield a better income at Simple or Compound Interest , but the most proper Reason is derived from the Nature of a Geometrical Progression decreasing ad Infinitum ; for instance , admit you have a Tenant in the Tenure or Possession of 1 l. per Annum , and you say to him , pay the rent now that will be due at the end of 1 Years , &c. ad infinitum . 2 3 4 and you will rebate him after the rate of Compound Interest . I say the Total of all those Payments shall never exceed 12 l. 10 s. 00 d. The Proportion for casting up the sum of a sinite Geometrical Progression runs thus , As the difference of an assumed extreme and its next inward mean is to the next inward mean ; So is the difference of the remote extremes to the sum of the Progression , except the assumed extreme . The reason wherof is , That if a rank of Numbers be in Geometrical Progression their sums and differences are likewise in the same Proportion . See 35 of 9 Book of Euclid , or Briggs his Arithmetica Logarithmica . Example . 6 , 18 , 54 , 162 , 486 ,   3 , 9 , 27 , 81 , 243 , 729 Wherefore it holds by Euclid . 6 As one difference Is to its Consequent — 9 So is the Sum of all the differences ( which is here the difference between the first and last term ) — 726 To the Sum of all the Consequents is 1089. Wherefore the sum of the whole progression is — 1092. And supposing this Progression to decrease infinitely , then will the first term be o , and the sum of all the Differences 729 , and it holds . As Wherefore the sum of this infinite Progression is 1093½ , and can never exceed it , and the said progression continued but in part towards the left hand , would stand thus , &c. 1 / 729 1 / 243 1 / 81 1 / 27 1 / 9 ⅓ I. 2. But admit the present worth of a Lease for a certain number of years be given , some third term must be further given , let that be the yearly rent , and then you cannot assign the rate ; ( and the contrary ) in this Case to find the rate is one of the most difficult Questions that commonly happens about Annuities , because the Proposition in the 5 , 6 , ( also 4th . ) Prop. will not hold conversly , there are but two terms in the Proposition given , which contain but a bare ratio , &c. therefore though out of Tables of Forbearance of Money at compound Interest , you can make those for Annuities , yet the converse will not hold . In this Case you must either by help of the 5 Prop. and common Logarithms , or of Tables of the present worth of Annuities , calculated to the best rate that shall suit the Inheritance , find the present worth of the Number of years proposed according to two rates assumed as near the truth as you can possible , and then if you have not lighted upon the given worth of the years assigned , use the help of this Approximation . As the difference of the present worths found , is to the difference of the assumed rates of Interest ; So the difference between the given worth and the truest of those Tryal worths ; To the difference between the rate of Interest of the tryal worth and that sought . And when the rate of Interest is truly found , compute accordingly the present worth of the years sought . But this were to send away the Reader , as if we could in this Case give no answer to the question , by help of the table here used ; whereto I answer , That if the worth of the Inheritance be assigned , repair to the following Proposition . But if not , let the Casualty as in the 6th . Proposition be reduced to a certainty ; viz. if it concern the Lease of a house which is a Casualty , abridge the Annual Rent , and then you may by the 5th . Prop. cast up the Value of any Number of Years therein . But herein I would not be misunderstood , as if when a Lease of a House of 1 l. yearly for 21 Years is sold for 8 l. 10 s. the which will purchase an Annuity or Certainty of 14 s. 5 ½ per Annum , and any Number of years in this Certainty shall be equivolent to as many in that Casualty , that therefore Tables made to both Rates , and a Computation to both the Yearly Rents must needs agree , because all Tables of Annuities are made for Certainties not Casualties . Or lastly , repair to the first and last Prop. and you will there find how to cast up the Amount of 1 l. Principal for any time , and at any Rate , where the true manner of such Equations is shewed . In this second Case is couched two usual Questions , most commoly propounded without sufficient Limits : As , 1. When a Lease is sunk by a Fine to a certain Yearly Rent , for a certain term of time , What the whole Lease is worth : Or , 2. What any number of years to be added , after the term in Lease is expired , is worth . In Order to the Resolution of either of these Questions it must be agreed how much the sunk Rent was , or at least as much given as before was required , and then as before you have a foundation whereon to raise a Rate of Interest , for there is now given the yearly Rent sunk , its present worth , and the time , and the Rate being found , you may then , according as is done in the 5th . Prop. resolve both these Questions . Prop. 8. A Table for the forbearance of Money at any Rate of Interest being in store to extend it to serve to all other Rates . It was before asserted that any such Table was a Table of Logarithms , and if filled up with Proportionable Numbers ( by 1. Prop. ) or otherwise suitable to such time or Decimals thereof , as may come in use , might for these purposes be more convenient than those already made , because it would admit a manifold Proof , as also because the differences would not be so vast near the beginning , but in some other respects inferiour thereto . And so contrarily , a Number being assigned to find the Logarithm thereto made , upon any kind of Rate or Supposition , it may easily be done out of the Common Logarithms , for the differences of all Logarithms are either equal or directly Proportional . Example first . As 74108 , Speidells difference of the Logarithm of 13 and 14. Is to 32184 d. Brigs his difference of those Logarithms ; So is 16000 , Speidells difference of the Logarithms of 62 and 63. To 69487 , the difference of those Logarithms in Mr. Brigs , or the Common Tables . Moreover Van Schooten in his Miscellanies gives you an Account of all Numbers under 1000 , that are prime or incomposite , to wit , 1226 in Number , viz. the which no other Number will divide , to the which if the differences be first found by Proportion , which in this Case having the two fixt Terms fixed , may be converted into a Multiplication or Division , and that Multiplier or Divisor being Multiplied by all the Digits into an Addition or Substraction , the Logarithms of all the Composite Numbers will easily be made out of the rest , by the continual Addition of the Logarithm of 2 , or otherwise . In the Table here used the time is the Logarithm , and the Amount the Number thereto belonging , and a Proportion accordingly may be applied to any kind of Logarithms , to find the Excess of time above a year , in which a 100 l. at 6 per Centum did amount to 108 l. But it may be more easily thus done . As , 02530586 , the Logarithm of the Amount 1 , 06. Is to 1 , viz. One year the time that 1 l. Principal was forborn ; So is , 03342375 the Logarithm of the Amount 1 , 08. To 1 , 32079 , the time required , and that is 1 Year , 3 Months , and about 26 Days , and thus the nearest way of resolving such a Proposition , having the Common Logarithms in Store , is by a Division of the Logarithms : But supposing no such Tables , it may be supplied by two Divisions by help of this Table , which I shall explain in two Cases . Sect. 1. The Amount of 1 l. being proposed , to find what time it must be forborn , at 6 per Centum to amount unto as much . Divide the given Amount by some Amount in the Table , next lesser , and that Quotient , again by the next lesser Amount , reserving the Quotient . If the time in the Tables belonging to the two first Divisors , and last Quote be added together , it is the time sought . Example . 1 l. in a Year at 8 per Centum did amount to 1 s. , 08 , in what time at 6 per Centum , shall it amount to so much .         In Decimals       Time     Dividend 108     1. Divisor — 106 — 1 Year 1   Quote — 1,018867 Second Dividend   2. Divisor — 1,014675 — 3 Months ,25     1,0041 Quote 26 days ferè ,07079         1,32079 But to save the Reader this trouble we have added the Equated time for these Rates .   l. years 100 l. shall 105 In ,83732 at 6 per 106 1 Centum 107 1,16114 amount 108 1,32079 unto 109 1,47896 And by the second Proposition the present worth of sundry payments due hereafter being computed , after the manner of this Example , a ●ue time may be found when the total of all those Payments may equitably be paid at once . Sect. 2. The Rate of Compound Interest , and the time being given to find what 1 l. Principal did amount to in that time . Or rather let it be thus proposed : How long shall one pound at 6 per Cent. be forborn to amount to as much as 1 l. forborn any space of time at any other Rate of Interest doth amount unto , and what is the said Amount ? By the time Proposed multiply the Equated time , next before found ( in the first Case ) that agrees to the Rate proposed , and you have the time sought , and what it shall amount , is found by the first Proposition . For instance , if 1 l. be forborn 18 years at 8 per Centum , what shall it amount to ? Or 〈…〉 How long shall 1 l. at 6 per Centum be forborn , to amount 10 as much , as if the said 1 l. had been forborn 18 years at 8 per Centum , and what is the said Amount ? By the former Example the Equated time or Logarithm of the Ratio found , was ,   years   1,3207 This Multiplied by 18 , the Product is 23,7726 To wit the time of forbearance . And the Product of the Interest Sums belonging to the true time is 3,99601 — or 3 l. 19 s. 11 d. the Amount of 1 l. forborn 18 years at Compound Interest , and the Amount of 1 l. being in Store , you see before that thereby all other Questions concerning Annuities are Resolved . But when the Law settles a New Rate of Interest , it may be more speedy to frame a Table thereto , or use such as the Scale of Interest , or other Authors afford . Now what I have hitherto wrote was chiefly to explain the Use of the Table , and to shew , That in case of necessity , with a little more pains , it takes away those Multitudes of Tables that are made , as well for quarterly as yearly Payments , at several Rates for Interest and Annuity Questions , and by reason it , with its Precepts , is contained in one quarter of a sheet of Paper , which I made my constant Companion in my Letter Case , that thou mightest reap the like benefit of it , it is also Printed apart . It is not my intent to inlarge upon a Multitude of Particular Questions , which would all be reduced unto or resolved by some of the former Propositions . That I leave to the Practice of the Studious . ADVERTISEMENT . MErcennus in the Preface of his Synopsis Mathematica , speaking of certain Supplements made to Geometry , and amongst the rest of Torricello's Hyperbolical Solid of an infinite length , found equal to a finite Cylinder , saith , That a certain Geometer found the like in a Space made by a curved Line drawn through the tops , all right proportional Lines ( supposed ) and by a right Line , on which the said Proportional Lines stand as Perpendiculars at a like parallel distance from each other ; if it may be said to be a Space which is not closed , unless perchance at an infinite distance , which Proportionals , he saith , would not long after be published : He wrote it in 1644 , but as yet I cannot hear of any such Treatise . Now , as I said before , the time being the Logarithms , and the Amounts the Proportional Numbers thereto belonging , by the help of the Curved Line he mentions ( which may also be described by mean or continual Proportionals in Lines without the help of Numbers ) the Logarithmetical Lines of Numbers , Sines , Tangents , Versed Sines , on Gunter's Rule may be Graduated , and the Meridian Line of Mercator's Projection , or the true Sea Chart ( being in the same Ratio with the Logarithmetical Tangents ) supplied , and whereas he mentions by one Curved Figure , there will also arise another for the same purpose , when the equal parts increasing in Arithmetical Progression , are raised as Perpendiculars on their Proportional Numbers placed in a base Line , and then the tops of those Perpendiculars joyned with a slexuous Curved Line passing through them ; but the Properties of these Figures as their Areas or Contents , Centors of Gravity , round Solids , and their first and second Segments , &c. are not as yet treated of by Geometers , and perchance might be more worthy their Contemplation than divers other Speculations , which seem to be of less Use , to which ( amongst many ) might be added the Curves made by the Annuity Lines , and the Curve in Mercator's Chart that represents a Semicircle of the great Arch , with a method of discribing it by Points , or Instrument ( if possible ) from its own Intrinsick Nature , without the help of Calculations or other Projections ; also how to cut a Cylinder that the Surface thereof unrolled shall render the Curve proposed of the like Nature , standing upon the Stage of Proposal , have troubled all France and Galileus for 35 years together , and since his death received their Resolution . A Table of Decimals of Days , which may serve for any Rate of Simple Interest , and a Table of Forbearance , or Amount of 1 l. Compound Interest at 6 l. per Cent. per Annum , for 365 Days and 11 Months . Days Decimals of days Amounts 1 ,002739726 1,000159617 2 ,005479452 1,000319336 3 ,008219178 1,000479037 4 ,010958904 1,000638768 5 ,013698630 1,000798522 6 ,016438356 1,000958305 7 ,019178082 1,001118111 8 ,021917808 1,001277942 9 ,024657534 1,001437800 10 ,027397260 1,001597683 11 ,030136986 1,001757592 12 ,032876712 1,001917526 13 ,035616438 1,002077486 14 ,038356164 1,002237471 15 041095890 1,002397482 16 ,043835616 1,002557511 17 ,046575342 1,002717580 18 ,049315068 1,002877667 19 ,052054794 1,003077802 20 ,054794520 1,003197919 21 ,057534246 1,003358083 22 ,060273972 1,003518273 23 ,063013699 1,003678488 24 ,065753425 1,003938729 25 ,068493151 1,003998995 26 ,071232877 1,004159285 27 ,073972602 1,004319605 28 ,076712329 1,004479948 29 ,079452055 1,004640310 30 ,082191781 1,004800712 31 ,084931507 1,004961132 32 ,087671233 1,005121577 33 ,090410959 1,005282467 34 ,093150685 1,005442545 35 ,095890411 1,005603068 36 ,098630137 1,005763616 37 ,101369863 1,005924190 38 ,104109589 1,006084789 39 ,106849315 1,006245414 40 ,109589041 1,006406528 41 ,112328767 1,006566741 42 ,115068493 1,006727443 43 ,117808219 1,006888171 44 ,120547945 1,007048924 45 ,123287671 1,007209703 46 ,126027397 1,007370508 47 ,128767123 1,007531338 48 ,131306849 1,007692194 49 ,134246575 1,007853076 50 ,136986301 1,008013983 51 ,139726027 1,008174916 52 ,142465753 1,008335850 53 ,145205479 1,008496859 54 ,147945205 1,008657870 55 ,150684931 1,008817905 56 ,153424657 1,008979967 57 ,156164383 1,009141054 58 ,158904109 1,009302121 59 ,161643835 1,009463306 60 ,164383561 1,009624470 61 ,167123287 1,009785661 62 ,169863014 1,009946877 63 ,172602739 1,010108118 64 ,175342466 1,010269386 65 ,178082192 1,010430680 66 ,180821918 1,010591909 67 ,183561644 1,010753343 68 ,186301369 1,010914719 69 ,189041096 1,011076110 70 ,191780822 1,011237532 71 ,194520548 1,011398513 72 ,197260274 1,011560453 73 ,200000000 1,011721952 74 ,202739726 1,011883485 75 ,205479452 1,012045028 76 ,208219178 1,012206604 77 ,210958904 1,012368207 78 ,213698630 1,012529835 79 ,216438356 1,012691489 80 ,219178082 1,012853169 81 ,221917808 1,013014874 82 ,224657534 1,013176606 83 ,227397260 1,013338368 84 ,230136986 1,013500145 85 ,232876712 1,013661955 86 ,235616418 1,013823790 87 ,238356164 1,013985650 88 ,241095891 1,014147538 89 ,243835617 1,014309449 90 ,246575342 1,014471385 91 ,249315068 1,014633352 92 ,252054794 1,014795341 93 ,254794520 1,014957357 94 ,257534246 1,015119399 95 ,260273972 1,015281466 96 ,263013698 1,015443560 97 ,265753424 1,015605678 98 ,268493150 1,015767824 99 ,271232876 1,015929992 100 ,273972602 1,016092892 101 ,276712320 1,016254415 102 ,279452055 1,016416663 103 ,282191781 1,016578938 104 ,284931517 1,016741243 105 ,287671243 1,016993540 106 ,290410960 1,017065919 107 ,293150695 1,017228295 108 ,295890411 1,017396994 109 ,298630137 1,017553130 110 ,301369863 1,017715585 111 ,304109589 1,017878065 112 ,306849315 1,018045851 113 ,309589041 1,018203108 114 ,312328767 1,018365664 115 ,315068493 1,018528254 116 ,317808219 1,018690866 117 ,320547945 1,018853504 118 ,323287671 1,019016177 119 ,326027397 1,019178857 120 ,328767123 1,019345733 121 ,331506849 1,019504313 122 ,334246575 1,019667083 123 ,336986301 1,019829875 124 ,339726027 1,019991694 125 ,342465753 1,020155541 126 ,345205479 1,020318411 127 ,347945206 1,020481309 128 ,350684942 1,020644233 129 ,353424667 1,020807182 130 ,356164393 1,020970158 131 ,358904119 1,021133159 132 ,361643845 1,021296189 133 ,364383572 1,021461593 134 ,367123298 1,021622323 135 ,369863024 1,021785425 136 ,372602749 1,021948558 137 ,375342476 1,022111715 138 ,378082202 1,022274899 139 ,380821928 1,022438109 140 ,383561654 1,022601344 141 ,386301379 1,022764607 142 ,389041106 1,022927895 143 ,391780832 1,023091208 144 ,394520558 1,023254549 145 ,397260284 1,023417914 146 ,400000000 1,023581308 147 ,402739736 1,023744727 148 ,405479462 1,023908170 149 ,408219188 1,024071642 150 ,410958914 1,024235137 151 ,413698640 1,024398660 152 ,416438366 1,024562213 153 ,419178092 1,024725785 154 ,421917818 1,024989386 155 ,425657544 1,025053613 156 ,427397270 1,025216666 157 ,430136997 1,025380346 158 ,432876722 1,025544052 159 ,435616448 1,025707783 160 ,438356174 1,025871541 161 ,441095900 1,026035316 162 ,443835626 1,026199125 163 ,446575352 1,026362972 164 ,449315078 1,026526834 165 ,452054804 1,026690723 166 ,454794531 1,026854641 167 ,457534256 1,027018579 168 ,460273982 1,027182546 169 ,463013708 1,027346543 170 ,465753434 1,027510559 171 ,468493161 1,027674605 172 ,471232887 1,027838677 173 ,473972613 1,028002774 174 ,476712339 1,028166899 175 ,479452065 1,028331053 176 ,482191791 1,028495226 177 ,484931517 1,028659434 178 ,487671243 1,028823659 179 ,490410969 1,028987914 180 ,493150695 1,029152196 181 ,495890421 1,029316503 182 ,498630147 1,029480838 183 ,501369873 1,029645199 184 ,504109599 1,029809584 185 ,506849325 1,029973997 186 ,509589051 1,030138442 187 ,512328777 1,030302901 188 ,515068503 1,030467393 189 ,517808229 1,030631911 190 ,520547955 1,030796454 191 ,523287681 1,030961026 192 ,526027407 1,031125622 193 ,528767133 1,031290244 194 ,531506859 1,031454895 195 ,534246585 1,031619570 196 ,536986311 1,0317●4●●● 197 ,539726057 1,031949●●● 198 ,542465763 1,032137521 199 ,545205489 1,032278534 200 ,547945215 1,032443342 201 ,550684941 1,0326●8174 202 ,553424667 1,032773034 203 ,556164393 1,032937920 204 ,558904119 1,033102832 205 ,561643845 1,033267771 206 ,564383571 1,033432736 207 ,567123298 1,033597703 208 ,569863024 1,033757985 209 ,572602756 1,033927789 210 ,575342478 1,034092859 211 ,578082204 1,034257956 212 ,580821929 1,034423079 213 ,583561656 1,034588204 214 ,586301382 1,034753404 215 ,589041108 1,034918606 216 ,591780834 1,035083763 217 ,594520559 1,035249089 218 ,597260286 1,035414370 219 ,600000000 1,035579678 220 ,602739727 1,035745010 221 ,605479453 1,035910371 222 ,608219179 1,036075759 223 ,610958905 1,036241173 224 ,613698631 1,036406611 225 ,616438357 1,036572078 226 ,619178083 1,036737573 227 ,621917809 1,036903089 228 ,624657535 1,037068659 229 ,627397261 1,037234207 230 ,630136987 1,037399804 231 ,632876713 1,037565430 232 ,635616439 1,037731080 233 ,638356165 1,037896757 234 ,641095891 1,038062462 235 ,643835617 1,038228192 236 ,646575343 1,038093948 237 ,649315069 1,038559733 238 ,652054795 1,038725542 239 ,654794521 1,038891378 240 ,657534247 1,039057241 241 ,660273973 1,039223106 242 ,663013699 1,039389046 243 ,665753425 1,039554988 244 ,668293152 1,039720972 245 ,671232878 1,039886952 246 ,673972604 1,040052974 247 ,676712329 1,040219022 248 ,679452056 1,040385096 249 ,682191782 1,040551198 250 ,684931508 1,040717326 251 ,687671234 1,040888480 252 ,690410959 1,041049661 253 ,693150686 1,041215868 254 ,695890412 1,041382102 255 ,698630138 1,041548363 256 ,701369864 1,041714649 257 ,704109589 1,041880960 258 ,706849316 1,042047303 259 ,709589042 1,042213669 260 ,712328768 1,042380062 261 ,715068494 1,042546482 262 ,717808219 1,042712928 263 ,720547946 1,042879401 264 ,723287672 1,043045901 265 ,726027398 1,043212426 266 ,728767124 1,043378979 267 ,731506850 1,043545559 268 ,734246576 1,043712164 269 ,736986302 1,043878797 270 ,739726028 1,044045456 271 ,742465754 1,044212141 272 ,745205480 1,044378853 273 ,747945206 1,044545592 274 ,750684932 1,044712357 275 ,753424658 1,044879150 276 ,756164384 1,045045969 277 ,758904110 1,045212813 278 ,761643836 1,045379786 279 ,764383562 1,045548585 280 ,767123288 1,045713509 281 ,769863014 1,045884074 282 ,772602740 1,046057440 283 ,775342466 1,046214445 284 ,778082192 1,046381477 285 ,780821918 1,046548530 286 ,783561644 1,046710807 287 ,786301371 1,046882733 288 ,789041097 1,047049872 289 ,791780823 1,047217036 290 ,794520548 1,047384229 291 ,797260275 1,047551448 292 ,800000000 1,047718696 293 ,802739727 1,047885989 294 ,805479453 1,048053264 295 ,808219179 1,048220589 296 ,810958905 1,048387941 297 ,813698631 1,048555320 298 ,816438357 1,048722726 299 ,819178083 1,048890158 300 ,821917809 1,049057400 301 ,824657535 1,049225103 302 ,827397261 1,049392616 303 ,830136987 1,049560107 304 ,832876713 1,049727721 305 ,835616439 1,049895336 306 ,838356165 1,050062933 307 ,841095891 1,050230335 308 ,843835617 1,050398261 309 ,846575343 1,050565953 310 ,849315069 1,050733679 311 ,852054795 1,050901432 312 ,854794521 1,051020810 313 ,857534247 1,051237020 314 ,860273973 1,051404858 315 ,863013699 1,051572714 316 ,865753425 1,051738180 317 ,868493152 1,051908515 318 ,871232877 1,052076452 319 ,873972603 1,052244425 320 ,876712329 1,052412418 321 ,879452055 1,052580440 322 ,882191782 1,052748489 323 ,884931508 1,052916563 324 ,887671234 1,053084180 325 ,890410954 1,053252794 326 ,893150686 1,053420949 327 ,895890412 1,053589108 328 ,898630138 1,053757318 329 ,901369864 1,053925553 330 ,904109589 1,054093831 331 ,906849316 1,054262131 332 ,909589042 1,054430478 333 ,912328768 1,054598766 334 ,915068494 1,054767113 335 ,917808219 1,054935559 336 ,920547946 1,055103982 337 ,923287672 1,055272407 338 ,926027398 1,055440912 339 ,928767124 1,055609416 340 ,931506850 1,055778678 341 ,934246576 1,055946508 342 ,936986302 1,056115093 343 ,939726028 1,056283706 344 ,942465754 1,056452343 345 ,945205480 1,056621012 346 ,947945206 1,056789705 347 ,950684932 1,056958443 348 ,953424658 1,057127172 349 ,956164384 1,057295946 350 ,958904110 1,057464748 351 ,961643836 1,057633576 352 ,964383562 1,057802434 353 ,967123288 1,057971313 354 ,969863014 1,058140222 355 ,972602741 1,058309157 356 ,975342467 1,058478129 357 ,978082193 1,058647110 358 ,980821919 1,058816127 359 ,983561645 1,058985178 360 ,986301371 1,059154242 361 ,989041097 1,059323339 362 ,991780823 1,059492461 363 ,994520549 1,059661616 364 ,997260275 1,059837952 365 ,100000000 1,060000000 Months Decimals Amounts 1 ,083333 1,004867 2 ,166667 1,009659 3 ,250000 1,014675 4 ,333334 1,019613 5 ,416667 1,024576 6 ,500000 1,029564 7 ,583334 1,034574 8 ,666667 1,039610 9 ,750000 1,044671 10 ,833334 1,049756 11 ,916667 1,054865 A Table of Forbearance , or Amount of 1 l. at Compound Interest , at 6 l. per Cent. per Annum for 50 years , and from thence continued to 100. Years   1 1,06 2 1,236 3 1,191016 4 1,262477 5 1,338225 6 1,418519 7 1,503630 8 1,593848 9 1,689479 10 1,790848 11 1,898298 12 2,012196 13 2,132928 14 2,260904 15 2,396358 Years   16 2,540352 17 2,692773 18 2,854339 19 3,025599 20 3,207135 21 3,399564 22 3,603537 23 3,819750 24 4,048935 25 4,291871 26 4,549383 27 4,821346 28 5,111687 29 5,418388 30 5,743491 31 6,088101 32 6,453386 33 6,840589 34 7,250025 35 7,686087 36 8,147252 37 8,636087 38 9,154252 39 9,703507 46 10,285715 41 10,902857 42 11,557032 43 12,250453 44 12,985481 45 13,764609 46 14,590486 47 15,465915 48 16,393869 49 17,377502 50 18,420152 60 32,987488 70 59,075911 80 105,795933 90 189,464433 100 339,398871 The Doctrine of DECIMAL ARITHMETICK , Simple Interest , &c. AS ALSO Of Compound Interest and Annuities : Generally performed for any time of Payment , or Rate of Interest , by help of any particular Table of Forbearance of 1 l. Principal . Abridged for Portability in a Letter Case . By John Collins Accomptant , Philomath . A Decimal Fraction is such a one whose Denominator is understood and not expressed ; and is an Unit with as many Cyphers following it , as there are Figures and Cyphers in the Numerator . Corollary . Wherefore the annexing of Cyphers towards the right hand of a Decimal alters not its value . A Decimal Fraction of Coin may be easily valued without the help of Tables . For each Unit in the first place is in value 2 s. 5 d. in the second place 1 s. and the rest Farthings ; but if any exceed 15 / 48 there must be ½ Farthings abated : So ,854 is in value 17 s. 1 d. ,418 8 4 ½ . Addition and Substraction in Decimals is the same as in whole Numbers , keeping the place of Units under each other . Multiplication in Decimals ; as many Decimal parts as are in both Multipliers , so many must be cut off from the Product ; which if it have not so many places the Defect is to be supplied with Cyphers towards the left hand . Division in Decimals is the Converse annex Cyphers sufficient ( if need be ) to the Dividend towards the right hand , that it may have more Decimal Parts than the Divisor , then as many Decimal Parts as are in the Dividend , so many must be in the Divisor , and Quote , when the Division is finished ; and in case of defect , the Quote is to be supplied with Cyphers towards the left hand . Simple Interest . Prop. 1. To compute the Interest of 1 l. for a Day . 6 / 105 is the Interest of 100 l. for a day , the 1 / 100 whereof is the Interest of 1 l. for a day , viz. 6 / 16500 , Or 6 divided by 36500 , namely , Days Interest of 1 l. 1 ,000164384 2 ,000328768 3 ,000493152 4 ,000657536 5 ,000821920 6 ,000986304 7 ,001150688 8 ,001315072 9 ,001479456 Prop. 2. Forbearance of Money at Simple Interest . The Interest of one pound for any number of Days may be taken from this Table by Addition , ( instead of a Multiplication , by the number of days , the trouble whereof is by the help of this Table spared ) and that Product multiplied by any other given Sum , makes the Interest thereof for the time given . Prop. 3. Rebate , or the present worth of Money due hereafter . Find the Interest of one pound , for the time given , and thereto adding an Unit. By it divide any other Sum given , and the Quote is its present worth . Prop. 4. Equation of Payments . By Prop. 3. Compute all the present worths , and then by Proportion . If all those present worths amounted to the Total of all those Payments , What did 1 l. amount to in the said time ? From the Result substract an Unit , the Remainder is the Interest of 1 l. for th● time sought , which divide by the Interest of 1 l. for a day , the Quote is the number of days sought . If you are to Equate an Annuity at Simple Interest , I presume a Compendium may be found in Mengolus his Arithmetical Quadratures , ( a Book I never saw ) who its probable by a Compendium gets the Fact of an Arithmetical Progression , and adds Fractions that have a constant Numerator , and an Arithmetical Progression for their Denominators . Days Decimals Amount 5 Years Amounts 1 ,002739 1,000160 1 1,06 2 ,005479 1,000319 2 1,1236 3 ,008219 1,000479 3 1,191016 4 ,010959 1,000639 4 1,262477 5 ,013698 1,000798 5 1,338225 6 ,016438 1,000958 6 1,418519 7 ,019178 1,001118 7 1,503630 8 ,021918 1,001278 8 1,593848 9 ,024657 1,001438 9 1,689479 10 ,027397 1,001598 10 1,790848 11 ,030137 1,001757 11 1,898298 12 ,032877 1,001917 12 2,012196 13 ,035617 1,002077 13 2,132928 14 ,038357 1,002237 14 2,260904 15 ,041097 1,002397 15 2,3●6●58 16 ,043837 1,002557 16 2,540352 17 ,046577 1,002717 17 2,692773 18 ,049316 1,002878 18 2,854339 19 ,05●055 1,003038 19 3,025599 20 ,054795 1,003198 20 3,207135 21 ,057536 1,003358 21 3,399564 22 ,060274 1,003518 22 3,603537 23 ,063016 1,003678 23 3,819750 24 ,065755 1,003839 24 4,048935 25 ,068495 1,003999 25 4,291871 26 ,071233 1,004159 26 4,549383 27 ,073973 1,004319 27 4,822346 28 ,076714 1,004480 28 5,111687 29 ,079454 1,004640 29 5,418388 30 ,082193 1,004801 30 5,743491 60 ,164386 1,009625 31 6,088101 90 ,246579 1,014472 32 6,453386 120 ,328772 1,019342 33 6,840589 150 ,410965 1,024335 34 7,250025 180 ,493158 1,029153 35 7,686087 210 ,575351 1,034093 36 8,147252 240 ,657544 1,039057 37 8,636087 270 ,7●9737 1,044●45 38 9,154252 300 ,821930 1,049●●7 39 9,7●35●7 330 ,904193 1,054093 40 10,285715 360 ,986316 1 , ●59154 50 18,420152 Mo. 1 ,083334 1,004867 60 32,927388 2 ,166667 1,0●9759 70 50,075911 3 ,250●●● 1,014●74 80 1●5,795933 6 ,500000 1 , ●29563 90 189,464433 9 ,750000 1,014●71 100 339,398471 The annexed Table is a Table of the Forbearance or Amount of 1 l. at Compound Interest at 6 per Cent. per An. This Table as to the Years , is composed by the continual Multiplication of 1,06 ( or by Addition tabulating the same ) and as to the Days may be supplied either by continual Proportionals , or the common Logarithms , which also are no other than Answers to Interest Questions , at the rate of near 26 per Cent. ( or the Amount is as 1 , to 1,2589292 ) supposing 1 l. in 10 Years to amount to 10 l. the Logarithms ( distinguishing the first Figure with a Conmma ) shew the Years and Decimals when it amounted to 2 l. 3 l. &c. And those Logarithms may be raised from the former . For the differences of all sorts of Logarithms of any four Numbers , are directly Proportional , and may be raised from any Table of Forbearance of Money at Compound Interest . Prop. 1. To continue the said Table , or to find the Amount of 1 l. forborn for any time proposed . Multiply those Amounts together that belong to such time , as added together makes the time given . Prop. 2. The Amount of 1 l. being given , To find the time of Forbearance . Search the Amount in the Tables , and divide by the next lesser amount , and that Quote again by the next lesser Amount , &c. reserving the Quotes , the time belonging to the Divisors , and the last Quote is the time sought . Example , 1 l. did amount to 1,08 in 1,32079 years . Prop. 3. To compute the Amount of 1 l. for any time at any Rate of Interest . By Prop. 2. compute in what time at 6 per Cent. 1 l. shall amount to as much as in one Year at the Rate proposed , that keep in store , and multiply by the time proposed , the Fact is the time in which at 6 per Cent. 1 l. shall amount to as much as it should do at the other Rate given ; to know which , use Prop. 1. Example , 100 l. did amount to 105 l. in , 83732 Years .   l.     Or , 1 l. did amount to 1,05 In Years ,83732 1,06 1 , 1,07 1,16114 1,08 1,32079 1,09 1,47896 1,10 1,63569 Admit it were required to find what 1 l. amounted to in 20 Years at 8 per cent . multiply 1,32079 by 20 , the Fact or Product is 26,14158 , and by Prop. 1. 1 l. at 6 per cent . in that time did amount to 4 6609. Now if the Amount of 1 l. be given , Annuity Problems are salved thereby . And for the advantage of this Proposition the Decimals of time were added . Prop. 4. Forbearance of Monies at Compound Interest . As an Unit is to its Amount in the Tables suitable to the time given : So is any other Sum to its Amount . Prop. 5. Discount of Money at Compound Interest , the Converse of the former . As the Tabular Number , Is to an Unit , its present Worth : So is any other Sum , To its present Worth. In Annuity Questions the Proportions are suited for yearly Payments ; if the Payment be half-yearly , then instead of ,06 ( or 1,06 ) and the Annuity in any term , take half a years Interest ,029565 , and the half yearly Payment ; and for quarterly Payments the Quarters Interest ,014674 , and the quarterly Payment , &c. Prop. 6. Forbearance of Annuities . As ,06 the Annual Interest of 1 l. Is to the Amount less an Unit of 1 l. forborn any term : So is the Annuity or yearly Pension , To the Sum for the whole Arrearages thereof . Prop. 7. Discount of Annuities , or their present Worth. As the Fact of ,06 and of the Amount of 1 l at Compound Interest for the time proposed , Is to the said Amount less an Unit : So is any Annuity , To its present Worth , To this Proposition belongs the Purchace of the Fee-simple . For yearly Payments divide the Rent 1 l. by the Interest ,06 the Quotes are 16 , ⅔ half-yearly   ,5   ,0295613   16,91303 quarterly   ,25   ,01674   17,07843 And so many pounds ( or years purchace ) is the Inheritance worth ( as may be proved from Tacquet's Arithmetick ) which Sums are no other than the Totals of the present Worths of the infinite Payments to be made . Hereto also belong Equation of Payments at Compound Interest : for having computed the present Worths , by proportion , you may find what 1 l. amounted to in the time sought , and by the second Proposition the time it self . Prop. 8. To find what Annuity any Sum of ready Money shall purchase for any time proposed . As the Amount less an Unit of 1 l. forborn at Compound Interest , the time proposed , Is to the Fact of , 06 , and of the Amount of 1 l. so forborn : So is any Sum of ready Money , To the Annuity it shall purchase . From these three Propositions the Tables in common use may be raised , if you put an Unit in the third place . Prop. 9. The Worth of an Annuity being proposed , To find the time of its Continuance . Get the difference of the Facts of 1,06 into the Annuity , And of ,06 into the Sum of the present Worth and Annuity , Then , as the said difference , is to an Unit : So is the Annuity , To the Amount of 1 l. for the time sought ( to be found by the second Proposition . ) Prop. 10. An Annuity , its present Worth , and time of Continuance proposed , To find the Rate of Interest . This is the hardest of Annuity Problems , and not to be resolved with Logarithms without Position or Trials ; the use is to find the value of any other Number of Years therein : To facilitate which , observe , That by Prop. 8. for 21 years at 6 per Cent. you may purchase Annuity of s. d. For l. s. 11 11 7 00 12 9 7 10 13 7 8 00 14 5 8 10 15 3 9 00 17   10 00 And these are the Rates for Leases of Houses of such a time , to wit , 1 l. a year for 21 years , is worth about 7 l. 10 s. or 8 l. as men agree , which is a certainty of 12 s. 9 d. or 13 s. 7 d. per Annum , whereby you have a direction to accord an abate for Casualty , and then use the 6 Proposition . Most of the many Propositions in the Learned Doctor Wallis his Arithmetick concerning Geometrical Progression ; as also in Mr. Dary's sheet of Algebra , may be easily resolved by help of the former Table : But this I have handled in my Supplements to Accomptantship , where also somewhat of Logarithm Curves , derived from Mean or Continual Proportionals , or Tables of Interest , and serve for making the Logarithm Scales of Numbers , Sines , Tangents , ( or Mercator's Meridian Line ) Geometrically . Prop. 9. More easily . As on Annuity , less the Fact of ,06 into its present Worth , Is to the Annuity : So is an Unit , To the Amount of 1 l. for the time sought . If the Payments be half yearly , for the Annuity in the first and third Terms , take half the Annuity , and for ,06 in the first Term as a Multiplier , take ,02956 the half Years Interest . For another Rate of Interest as 8 per Cent. take in ,08 as a Multiplier , and find the time in Years and Decimals by 2. Prop. as at 6 per Cent. which divide by the fitted Number of the Rate in Prop. 3. to wit 1,32079 , the Quote is the true time sought in Years and Decimals , which is easily reduced into Days by the Decimal Table of Days . Example . 50 l. a Year at 8 per Cent. is worth 490 l. 18 s. 2½ , or 490,91 , the time of continuance is 20 years . An Amount is proposed for 20 years to be 4,6609 , what is the Rate of Interest ? 1. The time in which 1 l. came to so much at 6 per Cent. is 26,4158 , found by the second Proposition . 2. Divide 26,4158 by 20 , the time proposed , the Quote is 132079 years . 3. 1 l. at 6 per Cent. in that time amounted to 1,08 , the Ratio sought . A PERPETUAL ALMANACK , To find what day of the Week the first of March shall happen upon . ADD to the Number 2 the Year of our Lord , and the fourth part of that , neglecting the odd , and divide by 7 , the Remainder is the day of the Week ; but if none remains it is Saturday , for you must account from Sunday , Monday , & c.. Example . So that the First of March is the First Day , that is , Sunday . The Number — 2 The Year of our Lord , 1685. 1685 The fourth Part — 421 Divisor — To find on what day of the Week any Day of any Month in the said Year hapneth . To perform this Proposition , the following Verse being in Effect a Perpetual Almanack , is to be kept in Memory . In this Verse are twelve Words relating to the Number of the twelve Months of the Year , accounting March the First ; wherefore the word proper to that Month , is An , and so in order of the Alphabet , which will never exceed Seven ; and the Number of the said Letter shews what day of the Month proper to the said word shall be the same day of the Week the First of March happ'ned upon , as the Example above . To find the Prime or Golden Number and Epact . Add to the Number 1 the Year of our Lord , and divide by 19 , the remainder gives the Prime . Multiply the Prime by 11 , and divide by 30 , gives the Epact . A Table of Primes or Golden Numbers and Epacts for ever . To find Easter for ever . Substract the Epact ( if less than 28 or 29 ) from 47 , if the Epact be 28 or 29 from 77 , the remainder is Easter limits ; so the first Sunday after the remainder , beginning from March , is Easter Sunday . To find the Age of the Moon . Add to the Epact the Day of the Month , and so many more as there are Months from March ( accounting March one ) the Sum if less than 30 is the Moon 's Age ( if more ) Substract 30 , ( when 31 Days in the Month ) but if 30 Days or less , Substract 29 , the Remainder is the Moon 's Age. To find the Southing of the Moon , and High Water at London-Bridge . Multiply the Moon 's Age by 8 / 10 shews the Southing , to which add 3 hours , shews High-water at London-Bridge . To find it another way . Multiply the Moon 's Age by 4 , and divide by 5 , the Quotient shews it , every Unit that remains is in value 12 Minutes , at full Moon reject 15 from it . Add to this 3 hours , shews High-water at London-Bridge . To find what Day of the Month the Sun enters into any Sign of the Zodiack , by the following Verse . Aries Taurus Gemini Cancer Leo Virgo ♈ ♉ ♊ ♋ ♌ ♍ Evil attends its Object , unva●●'d Vice , Libra Scorpio Sagittar . Capricorn Aquar . Pisces ♎ ♏ ♐ ♑ ♒ ♓ Vain Villains , jest into a Paradise . In which are twelve Words to represent the twelve Months of the Year , the first March , the second April , &c. and over the respective Words are the Characters of the twelve Signs of the Zodiack , thereby denoting , that in the Month to which the Word belongs , the Sun is in that Sign over head : And if it be required to know the day of the Month in which the Sun enters into any of those Signs ; if the first Letter of the Word , proper to the Month , be a Consonant , the Sun enters into the Sign thereto belonging on the eighth Day of the said Month , as in the Word Paradise , belonging to February , in that Month he enters Pisces the eighth Day ; but if it be a Vowel , as all the rest are , add so many Days unto eight , as the Vowel denotes ; now the Vowels are but five in Number . To know in what Degree of the said Sign he is for any other Day . If the Number of the Day of the given Month exceed the Number of that Day in which the Sun enters into any Sign , Substract the lesser from the greater , and the Remainder is the Degree . Example . On the 21 of April I would find the Sun's place by the Verse . It appears the Sun enters into Taurus on the ninth of that Month , which taken from 21 , there remains 12 , shewing that the Sun is in the 12 Degree of Taurus , the second Sign . 2. But if the Number of the Day of the given Month be less than the Number of that Day in which the Sun enters into the beginning of any Sign , the Sun is not entred into the said Sign , but is still in the Sign belonging to the former Month. In this Case Substract the given Day from the Day of his Entrance into the next Sign , and again Substract the Remainder from 30 , and the Remainder shews his place in the Sign of the former Month. Example . Let it be required to know the Sun's place the fifth of August on the thirteenth day of the Month the Sun enters into Virgo , 5 from 13 rests 8 , and that taken from 30 there remains 22 , shewing that the Sun is in the 22 degree of Leo , the fifth Sign . FINIS .