ABSTRACT
In this chapter, the authors investigates the two fundamental problems in compound interest: viz., to find the amount of a present worth, and to find the present worth of an amount. The next question is a more complex one: to find the amount and the present worth of a series of payments. If these payments are irregular as to time, amount and rate of interest, the only way is to make as many separate computations as there are sums and then add them together. But if the sums, times and rate are uniform, we can devise a method for finding the amount or present worth at one operation. A series of payments of like amount, made at regular periods, is called an annuity, even though the period be not a year, but a half year, a quarter or any other length of time.
