Pi (sometimes written π) is a mathematical constant whose value is the ratio Euclidean plane's circumference to its diameter; this is the same value as the ratio of a circle's area to the square of its radius. It is approximately equal to
The current record for the decimal expansion, if verified, stands at 5 trillion digits. Um yeah, I usually remember about 8.
It can be defined as the ratio of a circle's area A to the area of a square whose side is equal to the radius r of the circle:
There is a ton more on Wikipedia (isn't there always?). The other day I was watching a Stargate SG-1 episode and π was the key to the ancient writing. There are lots of sci-fi books and movies that use pi as the universal key to the language or code. Kinda cool.
Even cooler is all the goodies you can find online to celebrate. Think Geek (one of my all time fave geek shops) has a bunch of pi stuff just waiting to be bought. And don't forget the handmade goodies over on Etsy.
For me, I plan to make this embroidery piece from Urban Threads. Hurry on over - it's free right now :)