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 The Fed and How It Got That Way Here is a quick history of the Federal Reserve and an overview of what it does. 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. Saving for College This calculator can help you estimate how much you should be saving for college.