Imagine this. Say, you wanted to find the 3 of spades. You grab the deck, riffle down, remove the top part, and the card would be the 3 of spades?
This instructable well teach you how to do that.
Step 1: Beginning
A deck of cards. I recommend ellusionist.com
First, make sure that the desired card you want to "find" is at the top of the deck. Hold the deck in standered mechanics grip.
For those of you who dosen't know what that is, it's when you hold a deck with your thumb on one side, index finger on the top, and your other three fingers on the other side.
Hold the deck face down in mechanics grip.
SECRET OF PREFORMING THE MOVE:
Usually, the mechanics grip is natual, and shouldn't feel funny. This time, shift your 3 pinky-middle fingers to cover more of the card.
Step 2: The Pull
Riffle down to as much as the spectator wants you to. When he/she says stop, pull off the top part, BUT!!! because your 3 fingers are cover a lot of the top card, when you pull the top section off, the top card should remain there while the top section comes off the deck.
Do this fast, or people will be able to see.