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 Global and International Funds Investors seeking world investments can choose between global and international funds. What's the difference? How the Federal Reserve Works Each day, the Fed is behind the scenes supporting the economy and providing services to the U.S. financial system. Taxable vs. Tax-Deferred Savings Use this calculator to compare the future value of investments with different tax consequences.