Among all the blogs I read these days, I was surprised to see no mention of Pi Day (yesterday, 3/14) among them. The only mention I saw was on a law blog (The Volokh Conspiracy) by both Kenneth Anderson and Eugene Volokh.

Eugene also took issue with some definitions of pi, noting that a commonly used definition doesn’t properly state the definition of a transcendental number, confusing it with the definition of an irrational number.

A transcendental number is one that cannot be represented as a polynomial with integer coefficients. All transcendental numbers are irrational, but not all irrational numbers are transcendental. Both pi and e are irrational and transcendental.

CNN also had a nice write-up on Pi Day, although not on Pi Day but on the Friday before.

Pi is a number which has fascinated mathematicians and others all over the world for ages. Many have gotten pi tattooed on their bodies, including formulas that solve for pi; my favorite is this one that combines pi with beautiful typography. (If you want more science and math tattoos, check out the rest of the Tuesday Physics Tattoos.)

Others have created poetry from the digits of pi; perhaps the most extensive of these is the Cadaeic Cadenza. The Cadaeic Cadenza is a retelling of Edgar Allen Poe’s The Raven, but with each word letter-count matching up with the digits in pi. Even the name: “cadaeic”, when replaced by the positions of the letters in the English alphabet, is 3 1 4 1 5 9 2 (the first seven digits of pi).

Many have tried to memorize the digits of pi. I’ve known pi to 5 places for a long time, and recently have begun to expand upon that.

Entire books have been written about pi; the most widely known may be the Joy of Pi, written by David Blatner, and with a web page at One more unusual book is the seven-book series of 140 million places of pi from Pi Magus – who even has a 69-minute reciting of pi to 10,000 places.

So what did you do on Pi Day?