Today is Pi Day. Every March 14 is Pi Day. It has been around for a while, since 1988, actually, but today's Pi Day is special, because it is 3-14-15, which the astute reader already knows, represents the first five significant digits of the mathematical concept of pi -- π -- , which, as the ancient Greeks figured out, is what you have to multiply the square of the radius of a circle by in order to get its circumference.
Or, as it's usually represented, πr2 -- or "pi r squared".
Anyway, at 9:26:53 this morning, and again this evening, an even more special event will occur: π to ten digits, or 3.141592653 -- that's why today is a extra-special once-in-a-lifetime Pi Day.
Traditional celebrations of Pi Day include, naturally, eating pie and throwing pies. I intend to do both and I enthusiastically encourage all of you to celebrate as well.
Unless you were home-schooled and the Bible is your only source of knowledge. Then you can look at 1 Kings 7:23 and figure out your own version of π. You probably also subscribe to the Pie Are Round, Cake Are Square school of mathematics as well.
Much has been made of this apparent mistake by god in calculating the circumference of a circle -- see here for example -- but since I don't accept the Bible as a reliable guide in any other sense, I'm not going to squabble about what is essentially a rounding error by an "inerrant" god.
Nevertheless, Happy Extra Special Pi Day, everyone! We won't see another one like this for 100 years.