Pi (**π**) is an old number. It is found in the ratio of a circle’s diameter to its circumference. This might not seem like a big deal for our modern sensibilities, but this was important in the construction of arches for buildings and churches. And, let us not forget the wheel.

Circles are everywhere from wheels of a car, to wheels on a bike, to the shape of a pizza. If you don’t think pizza boxes don’t have to consider pi when making them, you are mistaken. The problem of a circle in a square has perplexed many mathematical geniuses over the centuries.

Talking about mathematicians, they have some funny words to describe pi. Mathematicians would call pi irrational, which means that you can never find a fraction that is equal to pi. For ancient people, or for anyone without a calculator, this is maddening. It is nice to be able to simplify pi. But, there isn’t a way to do that. For centuries, people looked for a fraction for pi and the closest is 22/7, but this doesn’t exactly equal pi. The other weird thing about pi is that it is transcendental, which means it will never be the solution to an algebraic expression.

Pi is a number that is everywhere but it just doesn’t fit in our standard way of thinking about numbers.

Another weird thing about pi is that it goes on for infinity, without end. Computer scientists have calculated pi for billions of digits. Like this …3.14159265358979323846264338327950288419716939937 … And on and on and on.

The last thing about pi is that it is use in statistics without our knowing. Whenever there is a bell curve shape, the mathematical expression for the bell curve, also known as a normal distribution, has pi in it. That means that pi is not only in every circle you see, but in any poll where an average is taken.

Pi is everywhere, which is why we take a day out of the year to celebrate it.

Happy 3.14!

For those serious about pi: