Lego Prediction

The perfect prediction effect, with an intriguing prop!

You walk out on stage with a jar full of legos, and ask the audience to guess how many legos are in the jar. You can one person name a number at random, or you can generate a number by asking three spectators to each name a digit. You then reach inside the jar with empty hands, and show that you've inserted a piece of paper with the count of legos. The audience guess is 100% correct!

The trick is self-contained, and nothing is palmed into the jar. It works 100% of the time, no matter what the audience says, and can be done with or without a secret assistant.