Pi Day is on its way and it's time to let that geek flag fly.

If you don't spend a lot of time in the nerd-o-sphere (pun totally intended), you may not realize that March 14 (3/14) is a beloved day to the mathematically aware.

I shouldn't have to tell CNET readers, but pi is a mathematical constant--the ratio of a circle's circumference to its diameter. The actual ratio is fairly close to 22/7--though pi to 12 places is 3.141592653589, not 3.142857142857--and comes in handy for calculating the area of a circle and other activities that even the nerdiest of writers like myself try to avoid on a daily basis.

My colleague Gina Smith, a contributor to CNET sister site TechRepublic, has a little less shame about her love for pi. She posted a long list of her favorite pi facts acquired over the years at aNewDomain (disclosure: I am a contributing editor for that site). Here are a few of my favorites:

 March 14--Pi Day 2012--is also Albert Einstein's birthday. Cool.  Calculating pi isn't as cool as memorizing and reciting it. There are actually clubs that train people to do this. I once saw a Japanese student, Kiroyuki Gotu, recite pi from memory during a competition. It took him 112 hours--he recited it accurately to 42,195 places before a crowd at the NHK Broadcasting center in Tokyo.  Pi is useful for another purpose. Use it to figure out your hat size. Measure your head--its circumference--divide the measurement by pi and round off to an eighth of an inch.  If you ever are assigned the task of estimating the height of an elephant, here's the trick. Measure the diameter of its foot and multiply that number by two. Then multiply the result by pi.  Would you believe you could calculate a circle the size of the entire universe (down to a proton) using pi to just 39 places? It's true.

Pi Day on March 14 has become a day to celebrate math and science in the United States, whereas much of the rest of the world also celebrates on July 22--or as they write it in the U.K.: 22 July or 22/7.

Celebrations will take place tomorrow in classrooms and at scientific institutions around the country, led by San Francisco's Exploratorium, whose "Prince of Pi," physicist Larry Shaw, is often credited with founding Pi Day.

The Exploratorium's pi-related activities will also be webcast and extend into Second Life. Princeton is another hotbed of 3.14 partying. There, they'll be celebrating both the constant and Einstein's birthday.

If you're hungry, you might want to see what's going on at middle and high schools within 3.14 miles of Raytheon's office locations, where the company will be delivering apple pies tomorrow (definitely the round kind). I suggest checking in with the main office, though, to avoid making the 6 o'clock news.

Finally, thanks to whoever sent me the huge beach ball covered with Pi Day propaganda in the mail yesterday. My postmaster is still confused. I told her to expect more come July 22.

How will you celebrate Pi Day? Let us know in the comments.