So 0 factorial divided by 10 minus 0 factorial, right? This is 10 choose 0. I'm choosing 0 left steps of the total 10 steps I'm taking times the probability of 0 left steps. So it's the probability of a left step, I'm only taking 0 of them, times the probability of a right step, and I'm taking 10 of those. So that's where this number came from, this 0.001. That's what the binomial distribution tells us. And then this one, similarly, is 10 factorial over 1 factorial over 10 minus 1 factorial, and that's how I get that one.