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. The Utility of Sector Investing Successful sector investing is dependent upon an accurate analysis about when to rotate in and out. Saving for College This calculator can help you estimate how much you should be saving for college.