Apparently, I missed e Day. More than likely, so did you. Don’t worry, though, there will be another chance this year, though you’ll be celebrating with Europeans.
Rhett Allain didn’t miss e Day:
Why is Feb. 7 e Day? Well, in the USA we use the Middle-endian date format. So, Feb. 7 would be commonly written as 2/7/13. Guess what? The first two digits of e are 2.7. If you live in other places you might use the little-endian date format. In this case 2/7/13 would be July 2. For those people, just consider this an early post.
But don’t get distracted. (Yes, my first question was the same as yours: “Really? It’s really called ‘Middle-endian’?”
But e Day is a celebration of e, the jealous little brother of π.
Allain offers his favorite definition: “e is the number that if you raise that number to the power x, the slope of the function is the same value as the function.”
And it just goes downhill from there. Or uphill, I guess, if you look at it on a graph. Sort of. The graph at right does not show you e. Maybe you could try reading the Wikipedia entry on e, but that’s the fun thing about being a poor mathematician and clueless excuse for a scientist.
Sometimes called Euler’s number after the Swiss mathematician Leonhard Euler, e is not to be confused with γ—the Euler–Mascheroni constant, sometimes called simply Euler’s constant. The number e is also known as Napier’s constant, but Euler’s choice of this symbol is said to have been retained in his honor.
By the time you get to the part about derangements, well, yeah.
Oh, right. e = 2.71828 (and a whole bunch of numbers after that; it’s irrational and trancendental, just like π).