You give an envelope to a spectator with a prediction.  You then show a deck of white cards with printed shapes (all different). You shuffle them very well and also give them to a spectator to shuffle. Then you wrap the cards with a rubber band and while the spectator is on the other side of the room you ask him to lift up any cards and remember the shape. Finally, ask the spectator to name the chosen shape and open the envelope revealing the matching prediction!

Quantity: