The "Rule of 72" is a formula that helps to determine the number of years that will be required for the value of an investment to double based on a particular interest rate. It is used to produce an estimated investment return using daily or monthly compounding but without additional contributions.
Here is an example of how the Rule of 72 is used: Let us assume you want to know how long it will take for your investment balance to increase from US$10,000 to US$20,000 using a yearly return of 5% without adding any further contributions. Simply divide 72 by 5, and you will see that it will take 14.4 years.