Card Trick

If you can memorize this chart, you can do a really cool card trick.

My basic statistics class gets to learn a new thing about me each class period.  Today, they learned that I like card tricks, especially mathematical ones.  Want to try?  Grab a deck of cards.

Count out 27 cards, because that is all that is required for this trick.  The next two instructions can be done in any order.

Pick any number from 1-27. Let's suppose you picked 23 like my student did this morning.

Go through the deck and choose a card as your card. Shuffle it anywhere in the deck.  Put it in a specific spot if you want.  It doesn't matter.

Here is the math part.  You need to take the number 23 and come up with three instructions.  In my picture, I want you to notice that 23 is in the middle of its most inside block.  It's block, is in the middle of the outside block.  Finally, the outside block is the bottom block.  OK, so it isn't the bottom, it is the far right, but I couldn't put a huge vertical photo in the blog.  You will need to remember middle, middle, bottom.

Now, deal the cards face up into three piles, one at a time, alternating piles.  To be specific, the first card defines the first pile, the second card the second pile, the third card the third pile, and then deal the rest accordingly.

While you are doing this, keep an eye out for your card.  You will need your participant to do the same thing later when you are performing.  Note which pile your card is in.  Once the piles are all turned over so that the cards are face down, you place the pile in the position of your first instruction: middle.  (Yes, I know that it didn't matter if we turned the cards over for that instruction, but for top and bottom it does.)

You do this again two more times, making sure you place the pile in the intended place.

Now, count out the cards from the top until you reach the 23rd card.  That is your card.  If you find yourself going "wow, cool!" then you just enjoyed some math.

Try it again for a different number.  Say, 6.  Can you tell that the instructions for 6 are bottom, middle, top?  Each number has a unique set of instructions that forces any card in the deck to the position you want it to be in.

Cool, huh?

For a slightly different explanation and a video tutorial, you can watch that here.