21 Cards Trick

1. Deal out 21 cards face up into three piles of seven cards each

2. Have the spectator silently pick one of the 21 cards

3. Collect the piles, placing the spectator's pile between the other two

4. Repeat steps 2 and 3 two more times. The spectator's card is the 11th card in the deck 

5. Deal out the cards face down, counting until you get to 11

6. Then, place that card face up

Hint: when dealing the cards, deal one to each pile, then a second to each pile, and so on.