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A shortcut to estimate the time it takes for someone to double his money, based on the interest earned, which is given by: number of years = 69 รท interest rate.
At a 3 percent interest, compounded annually, how long would it take the principal amount of an investment to double? The Rule of 69 says it takes about (69 รท 3) = 23 years for the money to double.
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by MathPlus July 04, 2017
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