# The Rule of 72 — a Shortcut That Makes Anyone Look Like a Math Genius

This is one of the most useful math tricks I know. It’s called “The Rule of 72,” and I use it at least a few times every week.

Let’s start with some examples of what we can do with it.

- If you asked me how many years it would take for an investment account to double if it pays 6% per year, I could tell you in a heartbeat that it will take 12 years to double.
- Or if you told me that you are hoping to double an investment in 8 years, my reply would be that you…