There is a simple magic trick that can be done with a set of six numbered cards.
- The Cub chooses a member of the audience, who picks a number from 1 to 63.
- The audience member indicates which of the 6 cards have the number
- The Cub then immediately tells the audience what the number was!
Of course, this is done using binary, and you simply add the numbers in the top left-hand corner of each card indicated by the audience member.
You can download and print the image here: