Amazing mathematical based card trick

This made the math-fail blog and it was just too funny not to share. The OP seems genuinely perplexed as to how it works. :smack:

To a casual observer (namely me) it’s a pretty impressive trick.

I’m sure a more accomplished magician could sell it better and true, it’s like I’ve always said, magic tricks, when explained, are usually pretty damned silly.

He really, really needs to work on his patter. He did a lousy job of selling the idea that the 3 chosen cards weren’t just, functionally, placed on top of each of the piles.

Well, that’s the thing - he wasn’t trying to sell anything, he didn’t understand the trick himself and was just explaining the mechanics. I for one didn’t catch that the cutting does absolutely nothing.

Yes, I think if you were performing this trick for real you might not mention the number of cards in each pile, as he does so often, and instead concentrate on the red herring of cutting the piles of cards.

I think the bit that needs to be downplayed is not the number of cards in each pile, but how you handle the cards after they’ve been cut - even without saying it in as many words, he does directly say ‘and then we put the next stack in a slightly different order on top of the picked card’.

You’d be better off just gathering the stacks and not letting the audience know that you’re gathering them in a specific order. Some may assume so, but with the right talk, you can distract them from paying attention to it.

Also, it may help to let the audience select which of the 15-card stacks they cut first - make it look like that matters and is out of your hands, even though what really matters is where the cards are put after the cut.

I did this trick for my daughters last night. Huge hit. I really played up that they had to tell me when they saw their card, and started complaining that they must have forgetten which cards were theirs each time I reached the end of a pile. By the time we got the end where all 3 cards were left, they were in hysterics.

I think his “I have no idea how this works” schtick is actually helpful in selling the trick. If he just sat down and did it and shouted, “Magic!” I would stare at him in disappointment and my brain would work it all out in the background. But watching it, I was like, “Well, this guy is a magician and even he can’t figure it out, so I’m not going to try.” It wasn’t until it was all over that I caught the error of that logic.

OK, I’m stupid.

Please explain why this works as if I was a five year old.

Thanks.

Simple explanation - you have to arrange the cards such that the 3 are in certain places in the decks. Specifically, the 6th, 22nd, and 38th cards. Then, as you do the “card up/card down” business over and and over, those cards will always be the last 3 left. Try it out yourself, or I can explain if you like.

So the hard part is getting the 3 cards they give you into those positions - I’ll call them X, Y, & Z. Card X goes on top of the pile of 10, which will become the bottom of the new deck, so it’s now card 42 in the deck. Next is the slightly tricky bit. You tell the person to cut the next pile wherever they want, and put Card Y on top, but you put the cut portion on top of the pile with Card X, then put the rest of the pile on top of that. So it doesn’t matter where they cut it - the entire 15 card pile is between Card Y and Card X. Card Y is now card 26 in the deck. The same thing happens with Card Z - the cut portion of pile 3 goes on top of card Y, then Card Z goes onto the remainder of pile 3, and that goes on top as well, so there are 15 cards between Card Y and Card Z. Card Z is now card 10 in the deck. Then, he puts the remaining 9 cards on top - Card X is at position 42, Card Y is at position 26, Card Z is at position 10. Finally, he takes 4 cards from the top and moves them to the bottom, so all the other cards move up 4 positions - Card X is at 38, Y - 22, Z -6.

And the 2nd part - as you flip the cards, alternating between up & down, you’re doing 2 things - throwing away the odd numbered cards (card 1 is up, 2 is down, 3 is up, etc), as well as reversing the order of the remaining cards (card 2 is down, but is now at the bottom of the face down pile). So after the first pass, card 6 becomes card 24 - it’s the 3rd card from the bottom of the new 26 card deck. Similarly card 22 becomes card 16 (11th from the bottom), and card 38 becomes card 8 (19th from the bottom).

Do it again to get a 13 card deck - card 8 becomes card 10 (4th from the bottom), card 16 becomes card 6 (8th from the bottom), and 24 becomes 2 (12th from the bottom).

Again to get a 6 card deck - 10 becomes 2 (5th from the bottom), 6 becomes 4 (3d from the bottom), 2 becomes 6 (1st from the bottom).

Do it one more time, and 2, 4, & 6 are the facedown cards, and the only ones remaining.

Ahh! Thanks. It was the cutting that was confusing me. I got that the selected cards were even numbers, but not how you kept them that way when cutting.

I should have watched more carefully.

I think I’ll amaze my family with this. :wink:

You know, David Blaine uses that approach. I’m not a fan of his Houdini style stunts but his street magic shows are always fun. “Excuse me, can I show you something interesting? I don’t know if this is going to work…”

I missed it, too. I didn’t get it till I read the comments on the math-fail blog page. The trick is that the cutting is a misdirect. It looks like you’ve changed the order of the deck, but all you’ve done is rearranged the cards within each 15 card filler stack. The actual target cards are placed so they have 15 cards between them.

As stated, he wasn’t trying to sell the trick, he was asking for an explanation. He was being as obvious as possible for people to figure it out. He wasn’t trying to obfuscate anything.

That film is from The Card Trick Teacher. His site is about explaining how card tricks work. Look at this example:

He’s not trying to sell the trick, he genuinely wants it explained. Now I don’t know how he missed something so obvious (it seems it should be obvious to someone well-versed in card tricks), but there you go. I guess he got lost in the shuffles and stacks.

There’s a trick with a similar mechanic (at least the part with the cuts doing nothing) called “the gambling computer” or something like that. This one also tends to be a big hit, but requires a little bit of setting up.

First, you want to get all the four aces on the top of the deck, then top that with any card. So, from the top down, you’ll have AnyCard-Ace-Ace-Ace-Ace. I usually perform this trick while playing a game of rummy, Go Fish, poker or something where it’s easy to load a stack of aces on the top of the deck without anyone noticing. Do it however you want. Start the trick with a couple false riffle shuffles that preserve the top five cards of the deck in order.

From here on out, you don’t touch the deck. Have your spectator cut the deck in half from right to left from your perspective. Now have the spectator cut the left stack to the left again, and the right stack to the right. So, from your perspective you have four stacks: the one on the very left has the very top of the deck as you had it, in order, so it should be AnyCard-Ace-Ace-Ace-Ace. Now, begin some patter about how you learned this great mathematical trick that floats the aces to the top of the deck (or however you want to frame this trick.)

Tell your spectator that the stacks are numbered one through four, from your right to their left (so it looks in normal one through four order from left-to-right in their perspective.) Have them pick up stack number one. Now, since it’s stack number one, you take one card from the top, put it on the bottom, then deal one card to the remaining three stacks. Have them replace the stack in the original position.

Now, they pick up stack number two. Since it’s number two, you take two cards from the top, and put one on top of each. Put back down. Stack three gets three cards from the top placed on the bottom, and then one on top of each. Put back down. Stack four gets four cards from the top and one put on top of each.

If you’re paying attention, you’ll note that when the four cards get placed on the bottom, stack four has the four aces on top. At this point, you explain how you shuffled the cards, and then your spectator was free to cut the cards however they wanted, they agree they weren’t forced to cut the cards in any way, etc., they handled the cards throughout the process, blahblahblah. You then knock hard on each of the stacks and flip each card over individually to reveal the four aces.

Whenever I show that trick to someone, the immediate reaction is for them to try it themselves and have it fail miserably. For such a simple trick, it gets a good reaction. I’m still not sure whether it’s better to have them handle the cards themselves or to handle the cards yourself after the spectator makes the cut. The advantage of handling the cards yourself is that it confuses the spectator as to where the trick is. With you handling the cards, there is a tendency to suspect that sleight-of-hand is involved, when it isn’t. Having the spectator handle the cards kind of eliminates this possibility. That said, I haven’t noticed any difference in reactions doing it one way or another.

I do a variant of this one all the time with my students, except all aces are on top, and for each stack you do the same thing: top three cards go on the bottom, then next three cards get dealt one each onto the other three stacks. The end result is the same (that is, what you’re doing to the first three stacks doesn’t matter at all, except that you’re putting one card each time on top of the aces atop the fourth stack; then for the fourth stack, you remove the three random cards you put on top of the aces, then deal an ace on top of each of the stacks).

For the finale, after the kids agree the stacks are thoroughly mixed, I ask different kids to put a hand atop each stack, and concentrate on “pulling” the highest card to the top. A face card is great, I tell them, a king is really good, but if they can get an ace, that’s the best. When they think they’ve pulled the top card to the top of the stack, they can turn it over. My amazement (and theirs) gets greater and greater as each kid turns over an ace.

Hee–I thought it was only kids that do this! It amazes me for real when people think that they can do what they just saw me do and have it turn out magic, as if there’s no trick involved.

That’s a really good frame (or whatever you would call it) to the trick. I’ll have to keep that in mind.

You’d think that, but adults do it to. I actually don’t usually frame it as a “math” trick, but that’s what the adults end up thinking it is, for some reason.