### What does it mean if the investment sales literature states that the future fund value of an ordinary annuity is determined using the simple interest formula method?

What does it mean if the investment sales literature states that the future fund value of an ordinary annuity is determined using the simple interest formula method? Explain what this means and also illustrate this by devising a calculation. (Assume that you have 20 years until you retire). What is the difference of a between