
Mind
Reader 
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? 