Given that the number 255 is eight ones, we can proceed from 0 to 255 by changing a 0 to a 1, always beginning at the left:
0 = 00000000 128 = 10000000 192 = 11000000 224 = 11100000 240 = 11110000 248 = 11111000 252 = 11111100 254 = 11111110 255 = 11111111