So this is, what's the probability of moving left, right, this is, so this is just saying, I'm just fixing a point, what's the probability, and you could change this, of my final position being 10. And then this essentially tells you that if I take 10 moves, then for my final position to be 10 to the right, I have to take 10 right moves and 0 left moves. That's a typo right there, it should be moves, not moves-ed. If I take 20 moves to end up 10 moves to the right, then I have to make 15 right moves and 5 left moves. And likewise, if I take a total of 80 moves, if I take 80 flips of my coin to make me go left to right, in order to end up 10 to the right, I have to take 45 right moves and 35 left moves, in any order. And it'll end up with 10 to the right. So what I want to figure out is, as I start taking a bunch of total moves, it's like my total moves, I mean here I max it out at 170, but you could kind of say, if I started flipping this coin an infinite number of times, I want to figure out what's the probability that my final position is 10 to the right.