Rule of 72:
Here is how the tool works.
If you divide your interest rate into 72 you will get the number of years it takes to double your money.
Example: 5% interest into 72 gives you 14.4 years for your money to double at 5%.
Disclaimer and Example:
This tool provides an approximation, not an exact amount.
For instance if you take $1 and compound it yearly for 14.4 years at 5% you will get $2.02. It is a good rule of thumb for figuring out how your investment will do.