Poker trick

Preparation: First take five cards: a red K, a red Q, a red J .. a black K and a black J, and pile them up. Take 4 more cards: take any 4 K, Q, J (only the color is different from the previous one, don't take monochrome) and hide it in advance.

Start: Tell the opponent that you can change the cards in his mind. Show your opponent a stack of five cards and let him stare at his chosen card 10 seconds. Then tell him to close his eyes until you say open them. When he closed his eyes, he changed a stack of four cards and hid five cards. When he opens his eyes, he will find that the card he is reading is missing.