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. Have A Question About This Topic? Name Email Address Message Thank you! Oops! Related Content What Smart Investors Know Savvy investors take the time to separate emotion from fact. Managing the Risk of Outliving Your Money Steps to help you sustain and grow your retirement savings. Lifetime of Earnings Estimate how much you have the potential to earn during your working years.