Place the 4 aces on the top of the deck. Have the spectator choose a card. Quickly count off 12 cards and have the card replaced so it is the 13th from the top. Now, tell the spectator that you have memorized the deck and know that their card is in the top half. Begin dealing two piles three cards at a time. Once you have dealt 24, add one to each. Discard the remaining cards. Tell the spectator their card could be in any pile. Pick up the one on the left and grasp the deck at the edges with on hand and top and bottom with the thumb and middle finger of the other hand. Pull so that you remove the top and bottom cards. Place these on top. Take the right deck and use a little patter while overhand shuffling so that the bottom card becomes the top. Now, you should 2 aces on top and one on the bottom of the left deck, and an ace on top of the right. Now place your hands on the decks and magically say you know it is on the left. Push the right deck forward. Deal the remaining deck one by one into two piles. Places your hands on top and discard the left. Deal the remaining cards into two piles. Place your hands on top and discard the right. Deal the remaining cards (you should have 3) into two piles. Discard the left. The remaining card is the chosen one. Now, most people know you simply counted where it was, using some patter, amazingly flip over the top cards of each of the 4 piles in front of you producing the 4 aces. Use good patter to make this more exciting.