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 When Markets React When markets shift, experienced investors stick to their strategy. Mutual Funds vs. ETFs Exchange-traded funds have some things in common with mutual funds, but there are differences, too. 5 Smart Investing Strategies Getting what you want out of your money may require the right game plan.