Thesaurarium mathematicae, or, The treasury of mathematicks containing variety of usefull practices in arithmetick, geometry, trigonometry, astronomy, geography, navigation and surveying ... to which is annexed a table of 10000 logarithms, log-sines, and log-tangents / by John Taylor.

PROP. VII. A yearly rent, or Annuity to continue any number of years, to find what it is worth in ready Money, at any Rate of Interest propounded.

What is 100 pound per annum to continue 30 years, worth in ready money at 6 l. per Cent. To find which first substract the Log of 100 l. the principal, which is 2. 000000 from the Log. of 106 l principal and interest for a year, whose Log. is 2. 025306 the remainder is 0. 025306: Then Multiply 0. 025306, by 30 the number of years of its continuance, it produceth the number 0. 759180; Then Divide 100 l. by 6

the rate of interest and the Quotient is 16 6667/10000, &c. which: 16 6667/10000, is the proportional parts of 100 l. the principal, then add the Log. there∣of which is 1. 221829 to the former Log. 0. 759180 it produceth 1. 981009, which is the Log. of 95 7215/10000 parts the Arrearages with the said some for that Time, then from those Arrea∣rages 95 7215/10000, substract the parts proportional of 100, to wit 16 6667/10000, the remainder is 79 ••••48/10000, which is the bare Arrearages for that proportio∣nal part; Then take the Log. of 79 0548/10000, which is 1. 897929, out of the which take the Log. found by Multiplication of years, to wit 0. 759180, there remains 1. 138749, which is the Log. of the value of the Arrearages in ready money, Then to the Log. 1. 138749, add the Log. of 100 l. principal, 2. 000000, it produ∣ceth this number 3. 138749; the Log. of 137 6 48/100, reduced is 1376 l. 9. sh. 7d. 80/100 or ⅘ fere: and so much is the said Annuity worth in ready money.