I can guess your number

[Qkchk:Me]

Another one of those 'I can guess which number you are thinking of' thingys.

I can read your mind

[Patar]

I'm sorry but that's just stupid.
The colours mean nothing and neither does the crystal ball or the doors
It knows what number you chose after you select the first group and the house, just by not having any overlaps.

[T-Thunder13]

well idont care how it did it, it freaked the shit out of me

[McJim]

'sjust basic arithmetic.

[Qkchk:Me]

Like Durrgghhh!