Effect:

The cards are shuffled by a spectator.

The performer will memorize all the cards that are dealt in the piles and all the positions of all the cared.

The cards are dealt into 2 piles (or up to 10 piles) face up.

While the performer turns his/her head away, the spectators turns a card face down in each pile. Then the piles are turned face down and the piles are stack together to one pile. Then the cards are mixed so everything is a big chaos. Face up into face-down cards. The performer takes the deck under the table, and ask which card the spectators are thinking off. Now the performer turns all the other cards face down so only the selected cards are face up. It looks like the performer has an incredible memory, that he/she knows where all the cards are in the deck. Easy to do. You can do it with a borrowed deck.

No marked cards.
You can use a borrowed deck.