Yay! It's Pi Day! March 14, when the first three digits of π, 3/14 are the date. Pi Day is exciting more than the usual amount of nerdy interest this year because today is the Pi Day of the Century, the only date this century when the first **five** digits of Pi will line up in a row: 3/14/15. And at 9:26 and 53 seconds you'll get to experience pi in **ten** digits.

So what is π, besides a Greek letter and something good to eat with ice cream? Pi, also called Archimedes' Constant, represents the ratio between the circumference and the diameter of a circle, or roughly 3.14. That's about 22/7 so for those of you who like multiple celebrations,you could also celebrate Pi Approximation Day on July 22.

The pi ratio, though not named π until the early 18th century, was known to the ancient Babylonians and Egyptians as a way of calculating the area of a circle. It was the Archimedes who first calculated it mathematically by inscribing smaller and smaller polygons inside and outside circles then measuring their perimeters. A record-setting computer calculation of π was made in 2014 to more that 13 trillion digits.

Pi has nearly endless applications in world from aeronautics and space exploration to building and navigation to sound and magnetism.

One of the beautiful mysteries of pi is that it's infinite and the digits, as far as anyone knows, never, ever repeat themselves in a pattern.

You can read a bunch about Pi, in books and online -- the internet is exploding with it today -- but a good place to start is with Petr Beckmann's A History of Π, available at the Main Library and branches. A book about pi can be your gateway to great (and instructive!) reading about math. Use the library's catalog to search Mathematics, for instance. Or Geometry.

Pi is even celebrated in a form of poetry called Pi Archimedes. A Pi Archimedes poem has 6 lines, with the number of words in each line representing the digits of pi: 3-1-4-1-5-9. Sort of like haiku, but mathematical.

If the day weren't special enough, March 14 is also Albert Einstein's birthday. And as a bonus, 2015 marks the centennial of Einstein's completion of his General Theory of Relativity.

## Comments

## What do you think?