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. Related Content How to Conquer the World - 5 Financial Strategies for Savvy Learn more about women taking control of their finances with this infographic. Comparing Investments This calculator compares the net gain of a taxable investment versus a tax-favored one. Tax-Saving Opportunities You Shouldn’t Overlook Tax laws are constantly changing and it can be difficult to keep up with all the tax saving opportunities that exist.