 And it's kind of amazing to think that with four cards you could do anything. But in fact, this is one of the favorite things for mathematicians is that there is great complexity in simple things if you look for it. And there's great simplicity then in that complexity. And so that's what I want to talk about a little bit. So everyone take your four cards. Can you hear me okay back there? So what I want everyone to do is take your four cards. Just keep them face down. Don't look at them. You can take one look if you want first. But after that just keep them face down and shuffle them however you like. Keeping them face down. Everyone content with how they shuffled it? Okay. And then maybe just for good measure give it one more cut. So give it a cut. That just means that you take some number of cards from the top and move them to the bottom. Okay. Okay, so now what I want you to do is take a peek. Just take a peek at the bottom card. So make sure you remember that card that's going to be your card. Okay. So it's important that you remember it. Okay. So everyone remembered their card. Okay. Now what I want you to do. So I'm going to ask you to do certain manipulations. You'll have choice in what manipulations you do. I'm going to try to watch everyone simultaneously. And then try to find everyone's card. Okay. By certain manipulations. Okay. So just listen to the directions. So first what I want you to do is take the top card. Move it to the bottom. So now you have hidden your card. Right. Okay. And once you've done that, I want you to take the top card and turn it over. Okay. And now here's where you have the choice. What I want you to do is just cut the deck card for your leg. So that means take zero, one, two, three, or four cards from the top. Move them to the bottom. Right. Just cut the deck card for your leg. Yeah. Okay. And then this is the move that may be new to you. What I want you to do is spread out the top two cards as if they're one card. Right. And turn them over. Everyone got that? Okay. So let's do that again. So cut the deck however you like. And then spread out the top two cards. Okay. Spread out the top two cards. And turn them over. I think most of you did that. Right. I'm watching. Okay. One more time. Cut the deck however you like. Cut the deck however you like. And we'll do that one more time. Spread out the top two cards. And turn them over. And then maybe just for good measure, cut the deck however you like. Okay. So now you've all been doing different things, right? You've all been cutting however you like, while you're spreading out top two cards and turning them over. But, okay, I'm now going to try to find your card. Okay. So let's see. Maybe first I want everyone to turn over the top card. Okay. Now take the top card and just move it to the bottom. Move one more card to the bottom. And now turn over the top card. And now what I claim is that three cards are going to be facing one way. One will be facing the other way. That's your card. Does that work? So how many people did that work for? Hopefully everyone. Okay. Most everyone who did it. All right. So if it didn't work for you, wait, one person didn't work for it. So if people are asking to do it again, I don't think we have enough time to do it again. If it didn't work for you, this is a trick based entirely on mathematics. If it didn't work for you, that means you didn't follow the directions quite right somewhere. But what is amazing is that just in four cards, there are so much mathematics inside that even though you have free choice on so many of the moves, I can still find your card. So that's it.