| − | The Rule of 72 is used to estimate [[Interest|compound interest]], specifically how long it takes money to double under a given interest rate. The number 72 is placed into the [[Numerator|numerator]] and the rate of interest in the [[Denominator|denominator]]. The quotient is the number of years needed for the money to double, up to a small [[Rounding_error|rounding error]]. | + | The '''Rule of 72''' is used to estimate [[Interest|compound interest]], specifically how long it takes money to double under a given interest rate. The number 72 is placed into the [[Numerator|numerator]] and the rate of interest in the [[Denominator|denominator]]. The quotient is the number of years needed for the money to double, up to a small [[Rounding_error|rounding error]]. |