The paired cards, four from the left and three from the right are then divided into two piles, forming two identical piles containing seven cards (an odd number). But because all the way through you’ve been stressing, “Here’s a pair”, your volunteer hasn’t noticed. They assume both piles are even. Yes, it’s another mind slip to cover the simple maths. With two piles of seven cards, adding the last single card turns that pile into an eight. So when you count them off two by two they are a full set of four even pairs. The spectator wonders, “Where did.
