## Precalculus (6th Edition) Blitzer

A sequence of equal payments made at equal time periods is called an annuity. Its value, A, after t years is given by the formula $A=\frac{P\left[ {{\left( 1+\frac{r}{n} \right)}^{nt}}-1 \right]}{\frac{r}{n}}$, where P is the deposit made at the end of each compounding period at r percent annual interest compounded n times per year.