Explanation of the "Flash Mind Reader"

It's really an interesting flash named "Flash Mind Reader".
The shockwave file below is from:http://qingke800.com/heart.swf
Thanks.

Then I am trying to find the trap within. It seems that every time, the crystal orb previews your choice correctly, whichever sign your result is. However, as many trick cracked before, maybe this one can be revealed by digit analysis too.

Supposed the tens digit of your number is a, and ones digit b, then the number's value is (10a+b), while the sum of the digits is (a+b). As a result, the difference between the number and the sum is(10a+b)-(a+b)=9a

Since both a and b are integers, 9a is certainly a multiple of 9, which can be divided exactly by 9. With 10<=(10a+b)<=99, the result- the difference fluctuate from 9 to 81, and is always 9's multiple.

Now look at the flash: Are all 9's multiples' signs the same?

Another trick it plays on us is that: it changes the sign of 9's multiples every time refreshed. So it's not easy for people to discover the mechanism.

Of course, confirmation of this hypothesis can only be made after anatomy on the file's inner codes.

Personally speaking, I believe miracles and God. But there are no many. Most are pseudo ones, created by people, just as tricks with goodwills. :)

Hai-Cheng Yu1:26 2007-2-25