Every time the spectator points to a pile, they provide a piece of information. They aren't just saying "it’s in there"; they are allowing the magician to trap that specific group of cards between two other groups of known size.
The fundamental rule is that the "hot pile" (the one containing the chosen card) is always placed between the other piles during collection. If you have three piles of 7 cards (21 total), placing the target pile in the middle ensures the chosen card is now somewhere between position 8 and 14. 84 card tricks: explanation of the general prin...
The core of the trick is a process of . By dealing cards into separate piles and having the spectator identify which pile contains their chosen card, the magician is essentially performing a manual "binary search" (or ternary search, if using three piles). Every time the spectator points to a pile,