Depends on what type of interest.
If it's simple interest then it is the original amount*interest rate*years.
If it's compound interest it is original amount(1+interest rate/times compounded)^times compounded*years.
The times componded means how many times a year it is compounded.
Annually is 1, semi-annually is 2, quarterly is 4, and monthly is 12.
Also the interest rate is in decimal form like 6% is .06.
Hope this helped!
