It's because we were able to run, during the manufacturing process, 20 colors for the X and the O, which is the name of the computer, and by mixing them on the manufacturing floor, you get 20 times 20: you get 400 different options there.
因为我们能够 在制造过程中， 各 20 色用在X和O， 这是计算机的名字， 将它们在制造现场混合， 20 x 20： 共有 400 种组合。