I mean, it's got an e in there. It's got a factorial, but you know, a lot of things have factorials in life, so not clear that that would make it a binomial theorem. But this is just the limit as you take smaller and smaller and smaller intervals, and the probability of success in each interval becomes smaller. But as you take the limit, you end up with e. And if you think about it, it makes sense, because one of our derivations of e actually came out of compound interest, and we kind of did something similar there. We took smaller and smaller intervals of compounding, and over each interval we compounded by a much smaller number, and when you took the limit, you got e again. And that's actually where that whole formula up here came from to begin with. But anyway, just so that you know how to use this thing, so let's say that I were to go out, I'm the traffic engineer, and I figure out that on average, 9 cars pass per hour.