Computer guys can explain what I am going to say better than me...
I just know that the sign # is called NumberSign in UNICODE - which is, I believe, the standard attribution of numbers -from 0 to 255 or from1 to 256? to simbols to print .
P.S. 256 is a power of two, so it corresponds to the number of possible numbers - written in base two - with less than 8 digits.