Coin Triangle Theorem

Each single move “turns” the triangle upside down. Th us, to get the fi nal triangle turned with its top down, you always need an odd number of single fl ipping moves.

Each single move fl ips a coin from one side to another (heads up to tails up, and vice versa). Th us, to get all coins in the fi nal position with all heads (A’s) up, you always need an even number of single fl ipping moves.