How Does this work?!
Simple, for example, if you pick a number between 90 and 99, the result would always be 81. Another one, a number between 49 and 40 would result in 36. Multiplies of 9 always have the same gifts, so the game's "guess" is always correct.
A fun thing, though
A fun thing, though
Yup. Proof:
Let A be the first digit of your number, B be the second digit. Therefore
Your number = 10A + B
End number = 10A + B - A - B = 9A
and A is an integer so the end number will always be a multiple of 9
Let A be the first digit of your number, B be the second digit. Therefore
Your number = 10A + B
End number = 10A + B - A - B = 9A
and A is an integer so the end number will always be a multiple of 9
I see now. I'm a little rusty at math, I haven't done any hard problems in....let's see, this is June, we got out of school in may, so....9 months. 
