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 When Markets React When markets shift, experienced investors stick to their strategy. The Investment Risk No One’s Ever Heard Of You face a risk for which the market does not compensate you, that can not be easily reduced through diversification. Saving for College This calculator can help you estimate how much you should be saving for college.