If deposits accumulates interest at annual rate [math]r[/math] and interest is paid [math]n[/math] times per year, then each dollar deposited grows to [math]\left(1+\frac{r}{n}\right)^{nT}[/math] after [math]T[/math] years. As [math]n[/math] gets large, the amount approaches [math]e^{rT}[/math], which corresponds to continuous compounding.