Select any card from the deck. For example, you have selected the ace of spades. Place that card on the bottom of the deck. This should be done before you begin the trick.
Ask your spectator to think of a number between 1 and 10. Explain that you will then ask him to deal to that number, and that he will take the selected card from the deck.
False shuffle or false cut the deck (see Resources for instructions). If performed correctly, the ace of spades will still be on the top of the deck. Once you've finished, ask your spectator to tell you the number he was thinking of. Say he has chosen the number 7.
Demonstrate to your spectator how to deal to his number. Dealing from the top of the deck, place seven cards on the table in a pile. Since the ace of spades was at the top of the deck, it will be the first card placed on the table and will be at the bottom of the pile. From your spectator's perspective, you are merely demonstrating what he needs to do next. However, the real reason you do this is to ensure that when the pile of seven cards is put back onto the deck, the ace of spades will be the seventh card from the top.
Pick up the pile and place the cards on top of the deck. The ace of spades will now be the seventh card from the top. Hand the cards to your spectator and ask him to deal down to his number and take the seventh card. He will pick the ace of spades. From here, you can take the trick in several different directions. You can either pretend to read his mind, or you can ask him to put the card back in the deck for you to find.
Note the top card in the deck. Say it is the queen of diamonds. Ask your spectator to cut the cards anywhere she likes, and place the pile of cards she cuts off into your hand.
Turn the pile of cards in your hand upside down so they are face up, and replace them on the top of the deck.
Ask your spectator to cut the cards a second time, this time a little deeper. As before, ask her to place the pile she cuts off into your hand.
Turn the pile in your hand face up and place them on top of the deck.
Get rid of all the cards that are face up, explaining to your spectator that the first card that is face down will be her card. This will seem fair because the spectator chose where to cut the deck on each occasion. However, following this process ensures that the first face-down card she comes to will be the original top card, the queen of diamonds.