Today is Pi Day because the date spells the first three digits (3.14) of pi, or π, the mathematical constant that represents the ratio of a circle's circumference to its diameter. This year, the event is even more special because, for the first time in a century, the date will represent the first five digits of pi: 3.14.15.

Do you celebrate pi day? Maybe you can have a pi party with 3 types of pies and 14 slices.

Some people get really nuts and recite as many digits in pi as they can. The current Guinness World Record is held by Lu Chao of China, who, in 2005, recited 67,890 digits of pi. He definitely has a lot of time on his hands.

I think I'm going to have a piece of pie today in celebration...you?