At a dinner last night, my friend Lan did a magic trick. Any ideas how it worked?
First, Lan took a number of cards out of a 52-card deck. I don't know exactly the number of card. To be sure that the cards are not prearranged, she gave me the cards and shuffled the set of cards by myself. After that she fanned cards and asked me to pick one card. I looked at them. I reput the card in any position in the deck of cards. I shuffled the set of cards by myself again and then gave them to her. She fanned cards, looked at them and picked the one that I chose. I don't really have any knowledge about card magic . So please forgive me if this is an obvious problem to you.
Here is the video showing the magic: https://streamable.com/zb5vp