Suppose you deposit $1000 in a savings account that compounds interest monthly. What is your account balance after 25 years if the interest rate is 3%?

The balance is computed from

A = P (1 + r/n) ^ (nt)

where P is the principal, r is the annual interest rate, n is the number of times per year interest is compounded, and t is the number of years.

A = 1000 (1 +.03/12) ^ (12*25) ≈ 2115.02

The account balance after 25 years will be $2,115.02.