A spectator holds one sponge cube in his closed hand. The magician touches his hand with a coin and the cube multiplies and there are two. Now the spectator holds the two cubes in his hand and with another touch of the coin the cubes multiply to three. Finally the three cubes are placed in the spectator's hand. The hand is touched with a coin and the spectator is asks if he believes that there are four?
No matter what the spectator says when he opens his hand there will be only one piece of sponge, however, it will be shaped like a giant 4.