Reference for Teachers

Example of How to Perform the Magic Trick

For example, suppose the person thought of the number 11.

When you show the card labeled "1" and ask, "Is the number here?" the answer will be yes; place the "1" card to your right.

When you show the card labeled "2" and ask, "Is the number here?" the answer will be yes; place the "2" card to your right.

When you show the card labeled "4" and ask, "Is the number here?" the answer will be no; place the "4" card to your left.

When you show the card labeled "8" and ask, "Is the number here?" the answer will be yes; place the "8" card to your right.

When you show the card labeled "16" and ask, "Is the number here?" the answer will be no; place the "16" card to your left.

Now you are ready to "guess" the number. Take the cards on your right (all the yes cards) and add the numbers appearing on their backs:

That total of 11 is the number you are after!