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. Well this is zero factorial is one by definition and so this is going to be five factorial over five factorial which is going to be equal to one. Once again, I like reasoning through it instead of blindly applying a formula, but I just wanted to show you that these, these two ideas are consistent. So let's keep going.