Image source: http://www.prosperitybankva.com/images/pb_pc.jpg
Computers use mathematical functions to determine the amount of interest or
balance in a bank account. For example, a computer program that determines the
amount of interest, i, earned in an account earning at a monthly interest
of 0.4% will use the formula i = b(1.004), where b is the average balance
of the account over the month.