Huh ??? Explanation anyone?

[P.C.]

This is cool.....I know there are a ton of these types of enigmas, and that there is most likely some kind of formula, but they still never cease to amaze me.  (I'm amused easily.

  Try it.

  [A href="http://www.milaadesign.com/wizardy.html"]http://www.milaadesign.com/wizardy.html[/A]    

[TehBorken]

 They use that special MRM (Mind Readng Module) on their server.

Here's a similar one: [a href="http://stupidstuff.org/main/mindreader.htm"]http://stupidstuff.org/main/mindreader.htm[/a]
 
And a really stupid one: [a href="http://stupidstuff.org/game/cardtrick/card1.htm"]http://stupidstuff.org/game/cardtrick/card1.htm[/a]

 

[Future Canadian]

My wife explains it thusly:
"If you write it out as an algebra problem, you always end up with a multiple of nine, no matter what the initial digits are. The value of the actual number, because of place value, is 10a + b. The number you subtract when you add the digits is just a + b. No matter what the digits are, the result is a multiple of nine, and if you look at the chart they show you at the end, every multiple of nine has the same symbol. It only LOOKS random. There's no trick -- it's just math!"
 

[P.C.]

I figured as much, but didn't have the mathematical soul to (nor the patience) to work it out.  Thanks FC and Mrs. FC. [img style="CURSOR: pointer" onclick=url(this.src); src="http://www.cheesebuerger.de/images/more/bigs/c007.gif" border=0]  (translation....I am developing a lazy mind)