Forty-Nine

The performer turns his back while a person among the group watching shuffles his own deck and discards three of them to leave a pack of only 49 cards.

The spectator now thinks of any one of the cards he holds, and deals them into seven face up heaps from left to right, a card at a time. He announces which pile, counting from left to right, holds his mentally chosen card. Though the performer’s back is turned, he says that he thought so, requesting the spectator to pick up the heaps by putting the 7th pile onto the 6th, the combined two upon the 5th, then on the 4th, and so on.

To make certain, however, the performer asks that the face up pack be dealt again into seven piles, a card at a time to each from left to right. Again the spectator names the pile into which his thought of card falls and the magus says he is quite certain of the card’s identity. The spectator collects the heaps in order as before and turns the pack face down.

Turning around for the first time, the performer has the spectator deal off a card at a time from the face down pack. At a sudden command to stop dealing, the performer turns up the spectator’s selection, even though he never has seen the face of a single card in the pack!

The method by which all the foregoing is accomplished depends upon simple calculation. After the first deal the number of the pack his card is in gives you the number FROM THE FACE OF THE PACKET HE NAMES AFTER THE SECOND DEAL THAT HIS CARD WILL LIE. If his card is in the first heap dealt on the first deal, it will be the face card of whatever heap it lies in after the second deal. If in the second heap (first deal) it will be next to the face of its heap after the second deal, etc. When he names its heap on the second deal you merely figure its position from the back of that heap adding seven for each heap that will go behind it when the deck is assembled, these of course lying over it when the deck is turned face down.

Suppose his thought of card lies in the third heap on the first deal, and in the sixth heap on the second. It must then be third from the face of the sixth heap, or fifth from the back of that heap. As five heaps will go behind it, we add 35 to 5, its position from the back of its (sixth) heap, and we therefore know it will be 40th from the top of the deck when same is turned face down.