In order to determine quickly how long it takes to double your investments at different rates, I usually use the rule of 72. I simply divide 72 by the annual percentage growth to obtain the time it would take me to double the investment. Thus if you earn 12% annually for example it would take you 6 years to double your investment.
At 6% it would take you twice as long or twelve years to double your investment.
In order to determine quickly how long it takes to triple your investments at different rates, I usually use the rule of 115. I simply divide 115 by the annual percentage growth to obtain the time it would take me to double the investment. Thus if you earn 5% annually for example it would take you 23 years to triple your investment. At 13% it would take you nine years to triple your investment.
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