Onto the table you place a sealed envelope and a 10, 20 and 50 pence piece. The spectator chooses one of the coins and the others are discarded. The chosen coin is flipped so it lands heads or tails.
The envelope is opened, turned upside down and a folded piece of paper falls out. The spectator opens the folded paper to reveal a prediction. You have correctly predicted the not only the chosen coin but whether it would land heads up or tails up.