Two hundred and fifty-five

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Two hundred and fifty-five
255
presentation
Roman CCLV
dual 1111 1111
Octal 377
Duodecimal 193
Hexadecimal FF
Morse code · · - - - · · · · · · · · · · 
Mathematical properties
sign positive
parity odd
Factorization
Divider 1, 3, 5, 15, 17, 51, 85, 255

The two hundred fifty five (255) is the natural number between 254 and 256. It is odd .

It has a special meaning in information technology (see below).

Prime factorization

The prime factorization of the number 255 is 3 × 5 × 17 , this decomposability into three different prime factors makes 255 the twenty-fifth smallest Sphenic number . The mentioned factors 3, 5 and 17 are the first three Fermat numbers .

Information technology

In the dual system , exactly 256 different values ​​can be represented with eight digits. This is important in computer science, since since the 1970s most computers have grouped the smallest units of information they process (the bits ) into octets (commonly known as bytes ) or a multiple thereof. The numbers 0 to 255 can be represented with an unsigned 8-bit integer variable . The number (decimal) 255 is the largest number that can be represented in the dual system with 8 digits (equal to 8 bits, namely as 11111111) and therefore occasionally occurs as a limit value in computer technology.

Examples:

  • When specifying color, the three channels red, green and blue are often given with 8 bits. Eg with HTML in the form of hexadecimal numbers. FF = 255 then corresponds to the max. Value (max. Brightness).
  • In simple networks, network masks in dotted decimal notation often contain the number 255, because they can be used to define a subnet with the same size as the network classes previously used on the Internet . The three classes A, B, C had the network length 8.16.24 bits and thus the network masks 255.0.0.0, 255.255.0.0, 255.255.255.0.
  • the computer game Pac-Man has 255 playable levels, because at level 256 the level counter, which is saved as an unsigned 8 bit integer, jumps from 255 to 0 and this is not handled correctly by the program.

See also

Individual evidence

  1. ↑ The RGB model (red / green / blue mixture). In: wiki.selfhtml.org The energy of understanding. SELFHTML eV, accessed on March 9, 2018 .