Compound interest is sometimes called one of the wonders of the financial world. Very simply, compound interest means you earn interest on your interest. The terms compounded daily, compounded quarterly, or compounded annually refer to when the interest is added to the balance and begins earning more interest.
The Rule of 72 is an easy way to estimate relatively accurately the impact of different interest rates over different periods of time. The point to remember is money doubles when the interest rate times the number of years equals 72.
While the Rule of 72 won’t give you precise results, it is an easy way to get a good estimate in a hurry.