The effect so clean it seems impossible! You ask the spectator to choose any card (no forcing involved!). After the spectator chooses the card, ask them to return it to the deck anywhere they want. Then give the spectator the deck to shuffle (shuffling can occur before they choose the card as well); then have the spectator put the deck back on the table. Tell your spectator a number, for example 12, then ask the spectator to hold the cards and count from the top 12 cards. As they reach the 12th card you stop them and ask them to turn it over - without touching, forcing, cutting, or slight of hand the 12th card appears as the chosen card!