To do a David Zanthor card trick, you can use any variant of numbers of cards. You just need to decide in advance the variant you want. Select 2 cards. Reveal them. Place the cards in the deck. Split the pack into two parts. Some will be face up and some face down. Then, you'll reveal that all the cards are turned in the right direction, except the chosen cards. This is easier, if you've master a split cut and the Sphengoli control. Control is the key with this trick. When you place the cards back into the deck, you will need to control their placement with your pinky. Then, place the cards on the bottom.