Mind Reader

[wsjb78]

I know, the instructions are in German but I just translate them:

http://andreas.apel.bei.t-online.de/gedankenleser.htm

1.) Think of a number with two digits e.g. 54
2.) Deduce the two digits from the original number e.g. 54 - 5 - 4 = 45
3.) Search in the list the result and the according symbol
4.) Concentrate extremly on the symbol! The click on that grey button field.