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 What Smart Investors Know Smart investors take the time to separate emotion from fact. The New Red Scare: Chinese Ownership of U.S. Debt China owns a portion of the total outstanding debt of the U.S. Government. What does it mean? 5 Smart Investing Strategies Getting what you want out of your money may require the right game plan.