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 What's My Potential Estate Tax? This calculator helps estimate your federal estate tax liability. What Is a 1035 Exchange? 1035 exchanges provide a way to trade-in an annuity contract or life insurance policy without triggering a tax liability. How to Make the Tax Code Work for You When you take the time to learn more about how it works, you may be able to put the tax code to work for you.