<P> In finance , the rule of 72 , the rule of 70 and the rule of 69.3 are methods for estimating an investment 's doubling time . The rule number ( e.g. , 72 ) is divided by the interest percentage per period ( usually years ) to obtain the approximate number of periods required for doubling . Although scientific calculators and spreadsheet programs have functions to find the accurate doubling time , the rules are useful for mental calculations and when only a basic calculator is available . </P>
<P> In finance , the rule of 72 , the rule of 70 and the rule of 69.3 are methods for estimating an investment 's doubling time . The rule number ( e.g. , 72 ) is divided by the interest percentage per period ( usually years ) to obtain the approximate number of periods required for doubling . Although scientific calculators and spreadsheet programs have functions to find the accurate doubling time , the rules are useful for mental calculations and when only a basic calculator is available . </P>
when do you use the rule of 72
when do you use the rule of 72
estimating an investment 's doubling time
estimating an investment 's doubling time