compound interest formula---
A is the accumulated amount of money, p is the principal amount, r is the interest rate in decimal form, n is the number of times per year compounding is done and t is the number of years in the contract.
For example, a contract is offered to pay 5 % interest, or .05, compounded quarterly, or 4 times per year, for 10 years on a principal amount of $1500. The total amount accumulated at the end of the tenth year will be: .05 divided by 4=.0125
.0125 +1=1.0125
1.0125 taken to the power** of (4 times 10) = 1.0125 to the power of 40=1.643619463
1.643619463 times $1500=$2,465.43
**please see the ^ symbol on actual scientific calculators