Think Of Any Number
Have a spectator choose any number between 1 and 63. Tell them to write it down and put the paper in their pocket. Claim that you can tell what the number is by listening to the tone of their voice as they answer yes or no to the following questions.
Close your eyes (or put on a blindfold if you want to get extra fancy) and show them the first of these cards. Ask if their number is on the card. When they reply, pretend you are really concentrating. Show the next card, ask again. Do this for all 8 cards. When done, pause and then announce in a loud clear voice what number they picked… it’s correct!
Here’s the secret:
Notice the first number of each card, in the upper left corner. 1 • 2 • 4 • 8 • 16 • 32. These are special numbers, each double the one before it. Ask your math or computer science teacher, they can explain more about them.
All you have to do is add the special number on each card that the spectator replies “yes”. For instance, let’s say the chosen number is “45”. The spectator will answer “yes” for cards 1, 4, 8 and 32. Add these numbers together and you get….. 45. As you are showing the cards, you’ll need to know what the special number is on each one.
Click on the number chart graphic to make larger. Then copy this graphic onto heavy paper, and carefully cut out the cards above. Ask an adult to help.