One or more spectators are invited to participate in 'Project-X'. he remembers any card he sees in the deck. Let's say the Four of Spades. The spectator himself now deals through the deck to find what where the card is located. Except, of course, the card isn't there! All he finds are the fifty-one other cards. No duplicates! Nothing added or taken away!
The performer now removes a prediction from an envelope that has been in view the whole time - it states, "Somehow you thought of the Four of Spades! The only card that wasn't there!!" The spectator is speechless. "Want to know why it's called 'Project-X'?" asks the performer. The spectator nods. The performer hands the envelope to the spectator. Inside is a single playing card with a big, black 'X' on its back. It is the Four of Spades!