I kid you not. Apparently there are a host of different opinions regarding when to celebrate Archimedes' constant. These include Pi Approximation Day on July 22, or 22/7; the 314th day of the year, Nov 10th - Nov 9th on leap years; April 26th, the day when the earth has traveled two radians of its orbit around the sun, also adjusted on leap years; and my favorite, March 14th at 1:59:26 pm...which is also Albert Einstein's birthday!
So, I'm giving my fellow geeks your four-weeks' notice. If I can remember it and get my act together, I think we should have pie on Pi Day, don't you?
If you're *really* feeling nerdy, you might also celebrate Avagadro's constant with molasses cookies on Mole Day (6:02 AM - 6:02 PM on 10/23), or by carving radishes and carrots and such into cubes on the next Square Root Day, 3/3/09.