And it's also, this is all a buildup for the binomial distribution, so you get a sense of where the name comes from. Let's write it in those terms. So this one, this one, this one right over here, the one way to think about that in combinatorics is that you had five flips and you're choosing zero of them to be heads. Five flips and you're choosing zero of them to be heads. And let's verify that five choose zero is indeed one. So five choose zero, let me write it right over here, five choose zero is equal to five factorial over, over, over five minus zero factorial, over, actually over zero factorial times five minus zero factorial. Five minus zero factorial.