Everybody repeat after me: three point one four one five nine.
I'm a humble wordsmith, so I'm stopping there. The rest of you more mathematically inclined types, feel free to keep adding to that list of significant digits, ad infinitum. But if you do, you might miss out on some of the other Pi Day festivities.
You could start by learning more about the near-mystical number--3.14 in its most severely abbreviated form, hence the March 14 (3/14) honors--at the official Pi Day site. There you can find out about the history of pi, how to use the number in a classroom to good effect, and how other people are celebrating the occasion. (Hint: The celebrations often involve a dessert that is both circular, as befits a number used in calculating the dimensions of a circle, and a homophone for the term itself.)
John Tierney offers further musings and amusement in his blog at the New York Times Web site: "Win a Pie on Pi Day"
The Huffington Post, too, has good pointers to various pi-related posts: "Pi Day: Time To Party!"
And be sure to check back here at CNET News.com later on Friday for video and other coverage from Kara Tsuboi and Daniel Terdiman, who'll be reporting from the scene at the San Francisco Exploratorium, which is where--according to Tierney--the Pi Day feasting began.