The Counting Card Trick

Shuffle a standard deck of 52 playing cards, and deal out a card face-up on the table. Then, starting with the number of the card, deal additional cards on top of that card to count up to 13. For instance, if you deal a 7, then deal 6 more cards on top of it, counting “8, 9, 10, 11, 12, 13.” Aces are worth 1, Jacks 11, Queens 12, and Kings 13. So, if you put down a King, you deal no cards on top of it.

Repeat this for 4 more piles. [You should have some cards left over in the deck. If not, start over.] Now flip all five piles over, so that the first card dealt in each pile is now face down on top the pile. Have someone choose two piles, pick them up, and add them to the deck. Have someone else choose two piles, and flip over the top card of those two piles. This leaves one pile with its top card face-down.

Now count off and remove from the deck the number of cards given by the top cards of the two face-up piles on the table. Then count off the magic number “10” cards in addition. The number of cards left in the deck *is* the number of the top card on the face down deck. Flip it over, and be amazed!

So, how does this work? Why is the magic number “10”? See if you can explain the secret of this card trick.