Second flip, there's two possibilities. And in the third flip, there are two possibilities. So 2 times 2 times 2, there are eight equally likely possibilities if I'm flipping a coin three times. Now how many of those possibilities have at least one head? Well, we drew all of the possibilities over here, so we just have to count how many of these have at least one head. So that's 1, 2, 3, 4, 5, 6, 7. So 7 of these have at least one head in them, and this last one does not.