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# The Rule of 72

Here’s a helpful way to estimate the amount of time or the interest rate you would need to double your money on savings or an investment. It’s called the Rule of 72.

**72 / interest rate = Years to double your money**

Let’s say you have an investment that’s earning 8% per year. Start with the number 72 and divide it by the interest rate, eight. 72 divided by 8 equals 9. This means it would take about nine years for your original investment to double. Try another example for yourself.

**The Rule of 72 may help you determine the appropriate level of funding for your savings and investments.**

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