Mind Reader
An Algebra Trick

This is a great trick to play on your friends. You can even design your own version of Mind Reader. It isall based on a bit of algebra, but it's really fun!

Try it yourself first using this online demonstration. Read the explanation at the end and then try it on your friends!

QUESTIONS:

How many different versions can you think of for this trick?

Does it only work for whole numbers between 1 and 10? Why or why not?

Does it work for negative numbers?

Another explanation