If you deposit money today into an account that pays 6.5 percent interest, how long does it take for your money to double?

The doubling period can be calculated by applying the following rules:

The rule 72

doubling period=72/the interest rate.


More accuracy can be achieved by applying the rule 69

doubling period=0.35+69/intrest rate

How long will it take $300 to double if it earns 7% compounding annually?