http://www.albinoblacksheep.com/flash/mind

go there, READ the options.

for example, choose 72, then do 7+2=9, so it will be 72-9=63. look at the symbol of it, it will find it

wow that mind reader is really accuate, ugh my head
anyway if u wait long enough its false sumtimes

It's a special property of the number 9. I remember we had to prove this property mathematically before...

uuhh math, this kind of games make me confuse Q_Q

try looking at the symbols, they change...

if u look at the symbol too long, the symbol u see will pop out XD

dude try and same number twice in a row, tricks it every time.
still, really cool. I would like an explanation if someone has one.

ahh i figured it out i Think.

there is a limited number of possibilities, and it puts the same symbol on all of those. it changes the symbols around every so often so it doesn't become obvious.

ya i tricked it 5 times well in the 1st time i was shocked on the third time it didnt guess it right

i tricked it only once, the other itsguess me right XD

2nd time, i owned the Crystal Ball.
First time it actually got it right.