Card Trick (Magic)

The Classic Force Magic

Effect:You fan through the deck, asking the spectator to choose any card he desires. He pick a card and without showing you, you can name the card!

Preparation:pick any card you want- this is the card you are going to force. Put the card back anywhere in the deck, maintain a little finger break below the card and you’re good to go.

Performance: The key to a successful force is timing- you must spread to the force card when your spectator is about to pick.
Say to the spectator, “I want you to reach in the deck and grab any card. It doesn’t matter which card.” Saying that the card doesn’t matter will prevent the spectator from taking his time and searching for a card

Fan through the cards, moving the cards left to right with your thumb.
Fan out the cards quickly at first so they have no chance of pulling out a card.
When the moment is right, fan to the break, slowly spread out the force card, and guide the card to their fingertips.

The spectator will inevitability pick the force card, since it is spread out the most.
Practice, practice, practice to get the timing of the force down.

Tips: This is a beautiful trick with endless possibilities. From the spectator’s point of view, it seems as though they had the opportunity to pick out any card. Rehearse this trick with different people to perfect the timing. Don’t worry about getting caught- most people never suspect a force. However, if they do not pick the right card (which will be unlikely after you master this trick) simply move on to another trick that involves the spectator picking a card

Source : http://learn-street-magic.com