A pen or pencil.
A piece of paper.
A Friend On the Phone
To Perform: Call up your friend and ask him to get a pack of playing cards. Tell him now to shuffle the cards and to deal them into two equal piles. Ask him to deal from left to right, back and forth, stopping any time, but the piles must contain the same amount of cards. He can place the remaining cards in the card box. Ask you friend to cut one pile by lifting up some cards and to look at and remember the bottom card of the cards in his hand. Tell him to complete the cut by placing the cards in his hand onto the other pile on the table. Now, ask your friend to one-by-one call-off the cards in the smaller, remaining pile. As he tells you each card, write them in a list on the piece of paper. He is not to know about this list. When he is finished, say, "Great, and your card is the... Umm. Oh, man, I feel so foolish! Your card is in the other pile, right?" After he tells you "yes", ask him to now call off those cards in the larger pile. As he is telling you those cards, list them on the paper continuing the list from the first one. Then, you tell him his selected card!
How? Let's say you list a total of 30 cards. Divide 30 in half to get 15. Count to the 15th card and that's his card. The selected card will always be at the position of the number of cards in the list divided by two.
