Every time this page loads a random set of colors is selected to fill 3200 10x10 pixel squares.
There are 16,777,216 possible colors, when you multiply that by the number of colors being generated you get 20,922,789,888,000 potential combinations.
The math is as follows: P((256 x 256 x 256), 3200) = 20,922,789,888,000
view the automated version here.
Thanks to @jsorrenti for being a passive math sounding board.