by Jim Craven

This is a card trick based on Set Theory. I use it to show how hidden algorithms in data or card sets can work like hidden agenda: They prescribe relationships, formulae, operations and steps to be performed leading to predetermined and discoverable outcomes.

1 Take a deck of playing cards with 52 cards (Jokers and Instructions Cards Out)

2. After thoroughly shuffling the cards, start turning the cards face up, each card face up on top of the previous card turned up. You will be forming separate piles of cards.

3. Each pile of card is formed in the following way. Suppose you turn up a four of clubs. Ignore the suit of the card. Now mentally, start counting cards from 4 upward with the first card, a four face up then pile on top of it cards (numbers and suits do not matter) 5,6,7,8,9,10,J,Q,K up to King. So if the first card was a four then you should have a pile of 10 cards including the four card. Then turn the pile of cards (as you turned them up) over face down to forma separate pile.

4. Suppose your next pile is formed by first turning up a Jack of whatever suit. Then you would think Jack, Queen King (each time counting up to King) in that case you would have three cards in that pile including the Jack. Then turn over the cards face down to form another pile. And lets say another pile is formed by first turning up a 6 of hearts (suit doesn’t matter) then count the next cards starting with the six as 6,7,8,9,10,J,Q,K so this pile should have 8 cards including the six. Then, again, turn over the cards (always keeping the order in which you turned then face up in place as your turn the whole pile over face down. If you turn up a King, then that card forms a pile alone.

5. If you are turning cards face up and mentally counting them and if your last pile does not have enough cards to reach up to a King, then leave it as a pile on which you will throw the other cards gathered up leaving three piles of cards.

5. Next, tell the people watching the trick to gather all the piles of cards up except any THREE piles of their own choosing and that you will leave the room as they decide which piles of cards to leave and which to gather up (to be placed on the pile of cards that did not have enough to count up to a King). Also gather up the piles with a lone King in it. Also tell the participants that they may move the piles of cards so that you do not know which they took and which they left, but if they do move the piles of cards spatially, then must move the whole pile (show them) in tact without disturbing the order of cards in the piles remaining.

6. Next tell them to leave THREE piles and gather up the remaining cards and place them on the pile that could not make a full set or pile of cards adding up to a King. Then shuffle the cards over and over. Note to the participants that there is no way you could know which of the many piles of cards they left and which they gathered up.

7. Next ask them to turn up the top card on two of the three piles of cards noting that not only could you not know which cards they left and which they kept, but you could not know before hand which two of the remaining piles of cards they would select to turn the top cards face up on.

8. Next, suppose the top cards on two of the three piles of cards are a 7 of clubs and say a Jack of Hearts. Add the two values of those cards together or 7 + 11 (Jack is the 11th card, Queen is the 12th and King is the 13th) = 18.

9. Now ask the participants to thoroughly shuffle the large pile of gathered up cards. Start counting the cards gathered up starting with 18 (7 + the Jack of teh two piles with top cards turned over). Next add another ten (all of this is done mentally). Whatever is left over (number of cards remaining) after 18 + 10 (always 10 added to combined values of top cards of two of ther three piles turned up) is what the top card in the third pile (not yet turned over) is. So if you count 18, then another ten, and if, after all of that, you have say 8 cards left, then the top card of the third pile is an 8 and so on.