I used the Future Value of an Annuity Dueto solve:

A friend creates an IRA (Individual retirement account) with an APR of 6.25%. She starts the IRA at the age of 25 and deposits $50 at the end of each month. How much will her IRA contain when she retires at the age of 65? Monthly interest rate I used 6.25%/12 months = .005; n = 40 years; P = $50 invested at end of each month. After doing the math on an TI-82 calculator, my Answer is $100,072.40. That is the WRONG Answer. It should be $106,595.63.