The third time the cards are dealt out, the selection will be the fourth card in which ever pile it ends up in. On the third deal, as soon as the spectator indicates which pile contains the selection, the magician knows that it is the fourth, or middle, card in that pile. If the magician gathers up the piles again, as before with the pile containing the selection in the middle, the selection will be the eleventh card in the 21 card packet.