What is 72 rule formula used in many years double your investment amount?

 The Rule of 72 is a simple formula used to estimate the number of years required to double an investment at a fixed annual rate of return. To use the rule, you divide 72 by the annual interest rate (expressed as a percentage). For example, if the investment grows at 6% per year, it would take approximately 72 / 6 = 12 years to double. This rule provides a quick way to understand the effects of compound interest on investments.