Doubling Your Money This calculator demonstrates the power of compound interest. You are viewing this website at a small screen resolution which doesn't support calculators. Click here to view this calculator. Share | Have A Question About This Topic? Name Email Address Question Thank you! Oops! Related Contents Saving for College 101 Here’s a crash course on saving for college. Life and Death of a Twenty Dollar Bill How long does a $20 bill last? What Is My Current Cash Flow? Assess whether you are running “in the black” or “in the red” each month.