An entertaining an fairly easy to perform effect.
Spectator picks a card, remembers it, and returns it. Performer claims that a pack of cards is like a computer and that he can program it to function like a lie detector. After the performer takes out some cards and reinserts them into the pack, the entire deck is handed to the spectator who answer and spells his answers by tabling cards. Was the card a face or point card? Was the card red or black? What suit was it? The bottom card of the tabled packet always shows the correct answer and therefore it is clear if the spectator told the truth or lied. At the end the spectator turns over the top card of the remaining pack and counts that many cards as the value of the turned over card. The spectator chosen card is at that exact location.
runtime: 6min 18s