mode probeing thing

[helacious_me_06]

how the hell does this work?! like if i actually think of the # and do the math it works! anyone know how this works?

[graphicsgirl]

basically it's any multiple of 9 (I believe) pick 2 numbers and work out the math seperately for both numbers you will see a pattern, then try picking the same 2 numbers and you will also see a pattern and all that changes is the symbol, the answers are all the same.