Happy Pi Approximation Day! Pi is 3.141592654 for the purposes of this discussion.

Pi Day and Pi Approximation Day are two holidays held to celebrate the mathematical constant π (pi). Pi Day is celebrated on March 14, which, in America, is 3/14. March 14 is also the birthday of Albert Einstein and the two events are sometimes celebrated together. Pi Approximation Day is held on July 22, which, in Europe, is 22/7. The fraction 22/7 is an approximate (and slightly more accurate) value of π. However, on 12 March 2009, the U.S. House of Representatives passed a non-binding resolution (HRES 224), recognizing March 14, 2009 as National Pi Day.

If you wanted to get really geeky, you could also celebrate the Pi Minute on March 14 at 1:59 am, and Pi Second at 26 seconds. In 2015, a Pi Second with an accuracy of 10 digits will be held on 3/14/15 at 9:26:54 in the morning. Pi Day in 2016 will be special as well, since 3/14/16 equates to a rounded version of pi.

The first Pi Day celebration was held at the San Francisco Exploratorium in 1988, with staff and public marching around one of its circular spaces, then consuming fruit pies. The museum has since added pizza to its Pi Day menu. The founder of Pi Day was Larry Shaw, a now-retired physicist at the Exploratorium who still helps out with the celebrations. Here at Fresno Pacific University, the mathletes celebrate Pi Day with a pie fundraiser. They buy pies from Marie Callendar's and set up tables in front of the cafeteria and on the first floor of AIMS Hall of Math and Science.

Of course, I don't think we'll be getting quite as into the spirit of Pi Day as MIT Admissions, who releases decisions at 1:59 pm on Pi Day, or MIT students who in 1994 put a campus police car, number pi, on top of their Great Dome. Or did they?

To learn more, visit these cool sites:

Pi Day at the Exploratorium
Pi Day .org

Some entertaining videos to watch:

The Pi Song - singing Pi to 50 places.
Say that Funky Number, Math Guy - a video by Al G. Bra and Cal Q. Lus that you have to see to believe.
Pi Pi Mathematical Pi Song (Full Version) - "Pi, pi, mathematical pi" is the first line of the chorus. ((The first time I heard this song was in Academic Decathlon... I believe a guy named Marcus Cope was singing it. Hey, Marcus, what's up? Happy Pi Approximation Day!))
The Tales of Fort Lego: Pi Day - Silliness with Legos and pies.
Pi Day - cute pi day short in preparation for Pi Day 2010... which has passed, but it's still cute.