The magician puts 2 decks of cards on the table.
He asks a spectator to name a card and choose one of the two decks.
The magician hands the chosen deck over to the spectator and asks him to shuffle it. The magician will then try to find the named card as quickly as possible. To this purpose, he takes out his phone and launches the timer app.
After showing how the timer works, the magician requests the spectator to tap on the timer’s start button.
At this point, the magician begins to deal the cards, turning them face up one at a time, into a pile on the table. As soon as he gets to the spectator's card, the spectator has to stop the timer.
To the spectator, there is nothing magical in this demonstration… But wait !
The magician then asks the spectator to total the minutes, seconds and milliseconds displayed on the timer and to announce the result.
To conclude, the spectator takes the other deck and starts counting cards, dealing them one at a time on the table. After dealing as many cards as the total of the timer, he will get to the chosen card !