Prepare for the trick by separating a deck of cards into two smaller decks: one of only black cards and the other only red cards.
Step2
Lay the decks out side by side on a table and have the volunteer choose a deck.
Step3
Have a volunteer pick a card at random from the deck he or she chose.
Step4
Have the volunteer memorize the card and show it to the audience, and tell him or her not to show it to you or tell you what it is.
Step5
Have the volunteer place the card into the other deck at any location.
Step6
Shuffle this deck several times.
Step7
Look through the deck. The volunteer's card will be a different color than the other cards in the deck.
Tips & Warnings
One of the most important rules of magic is to never reveal how a trick is performed. If you do, your audience will be disappointed and everyone you know will start doing your trick.