1. The problem statement, all variables and given/known data I am given this question: what is the monthly payment necessary to ammortize a loan of $100 000 at 2.3% compounded monthly for 20 years. I know the answer to the above: it is done by using the ammortization payment formula, in this case: R = 100 000 ((0.023/12)/(1-(1+0.023/12)))^-240. But then it asks, "how much interest will you have paid after 20 years". Is there some algebraic way to figure this out? 2. Relevant equations Loan: 100 000 Interest rate: 0.023 Time: 20 years Not sure we need an equation. 3. The attempt at a solution If there is no algebraic way to figure this out, I fear the only way it can be done is to draw an enormous table. Can it be done any simpler?