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 Should You Invest in Exchange Traded Funds? There are hundreds of ETFs available. Should you invest in them? Global vs. International: What’s The Difference? International funds invest in non-U.S. markets, while global funds may invest in U.S. stocks alongside non-U.S. stocks. 5 Smart Investing Strategies Getting what you want out of your money may require the right game plan.