Today, April 15, 2007, marks the 300th birthday of Leonhard Euler. Not that he’s still alive or anything. Euler (rhymes with spoiler, NOT Bueller!) was the most prolific mathematician of all time, publishing more than 800 papers (!) in his lifetime. Have you ever used the number *e*? How about the number *i*? Have you ever used the notation f(x) to indicate a function? Remember The Most Beautiful Equation in the World?

Yeah, those were all him. And there are about a bajillion other things in math that he discovered and/or are named for him: Euler characteristic, Euler’s theorem (there are actually several of these), Euler identity, Eulerian path, Euler-Mascheroni constant, Euler’s totient function, and so on. He was one smart dude.

Mark Dominus over at The Universe of Discourse has a more detailed discussion of a few of these things, instead of repeating it I’ll just send you over there to read it if you’re interested. =)