Pi can be used to measure many different things including hat size | Hey Ray
There is Pi all around us, in ways you may not have seen before. If you remember from school, Pi is the ratio of a circle's circumference to its diameter. It is a number that is usually written as 3.14. Around Pi Day, or March 14, you know 3-1-4. We have shown you how Pi works with pizza, the best sized pizza to buy, and other ways Pi can show up in the past.
If you ever bought a fitted hat, you have had Pi on your head! You may have seen the number on the inside of the hat showing its size. If you are like me, you just try on a bunch of hats to figure out what number is your ideal size. That number, though, is related to Pi, so you can figure out your hat size a different way.
You may have heard of doing math in your head. This time we are going to do math on our head. To do this, you measure the circumference of your head. You take that number and divide by Pi, or 3.14. If you change the decimal to a fraction, that will be your hat size. For my head, the circumference is 23 and 5/32 (.1575). Divide that by 3.14 and you get 7.375 which is 7 and 3/8. That is the size of my hat.
Hats off to Dr. Neil deGrasse Tyson, who pointed that out in a tweet.
You can also tell how big someone's head is by doing that math backwards. If you take someone's hat size and multiply by 3.14, you will come up with a very close approximation of the circumference of their head.
I am not sure why that was the preferred method of doing this instead of just using the circumference, but if we just used that measurement, we wouldn't have anything to talk about around Pi Day!
