Can someone explain how this works?
Mystical Ball

This is freaky
Screw the whales, save the subjunctive!

Hint 1: 10x + y  (x + y) = 9x
Hint 2: Does the chart stay the same each time you click on the crystal ball?<i>Our lives begin to end the day we become silent about things that matter.</i>  MLK

hmm well it freaked me out because it got the symbol right the first time. But when I tried it again it was wrong... hmm..
<span style="color: green">"Don't be a Dork! Wrap your Pork!" </span><br /><br />

If the Web page refreshes properly it should always work.
<i>Our lives begin to end the day we become silent about things that matter.</i>  MLK

I'd like to add more hints here [so anyone can perfectly understand what SteveA says):
1) Each integer number (0<=x<100) can be represented like this:
N=(10*X)+(y), where 0<=x<10, 0<=x<10 and x,y integers
2) The symbols repeat themselves and they are totally 9 symbols...
3) Every time, the 00,09,18,27 (multiples of 9) will have the same magic "symbol" and whatever number you choose randomly, you'll end up in a multiple of 9.Never to surrender, never to retreat...<br />Give your last breath to defend it

If you pick any number on the board it will always give you the same symbol. Try it. The symbols rearrange each time you hit "try again" so that you get a different on each time.
It didn't work for you Ntro becasue you didn't pick a number again. 
It hit me while I was in the shower this morning (I do my best thinking when I'm naked). Any possible answer is a multiple of 9. All multiples of nine are associated with the same symbol.
Yeah me!Screw the whales, save the subjunctive!

LOL. yea i do my best thinking while im on the toilet

All multiples of 9 have the same symbol and it's just a fact that adding two #s and subtracting that # from the original will always give a multiple of 9...TADA!
She gasped and she sighed and she called my name.

That's cuz it was showing you the symble for the number you would have picked next. Muhahahaha
Big, fat, wet, juicy smiles!