This is a real cool game. It just seems like magic.
- You choose a 3 or 4 digit number
- Jumble the digits in the number to get a brand new one
- Subtract the smaller one from the bigger one
- Ommit one digit from the result and tell fido about the other digits
- He reads your mind and BOOM, he knows that number you ommited
Give it a try here. If you are not into the phsycic powers of Fido, there’s another options. It’s a simple math game with a proof !
I don’t really know about the proof but you’ll find that the difference between the 2 numbers is always divisible by 9 so the digits of the difference should sum up to a multiple of 9. This way Fido can guess the missing number.
For more about this explanation check the comments on this site.