The Rule of 72 Do you know how long it may take for your investments to double in value? The Rule of 72 is a quick way to figure it out. Share | Related Content It Was the Best of Times, It Was the Worst of Times All about how missing the best market days (or the worst!) might affect your portfolio. What’s Your Investment IQ? You make decisions for your portfolio, but how much do you really know about the products you buy? Try this quiz What Is My Risk Tolerance? This questionnaire will help determine your tolerance for investment risk.