Signed number representations

In <a href="/facts/Computing/Kghtm9fX">computing</a>, signed number representations are required to encode <a href="/facts/Negative_number/LzErzCmI">negative numbers</a> in binary number systems.
In <a href="/facts/Mathematics/pxTouaz4">mathematics</a>, negative numbers in any base are represented by prefixing them with a minus sign ("−"). However, in <a href="/facts/RAM/DuD4bxh6">RAM</a> or CPU <a href="/facts/Processor_register/32RvbUdz">registers</a>, numbers are represented only as sequences of <a href="/facts/Bit/RwfjaYSv">bits</a>, without extra symbols. The four best-known methods of extending the <a href="/facts/Binary_numeral_system/a6JDSRPs">binary numeral system</a> to represent <a href="/facts/Signed_number/z0xollg1">signed numbers</a> are: sign–magnitude, ones' complement, two's complement, and offset binary. Some of the alternative methods use implicit instead of explicit signs, such as negative binary, using the base −2. Corresponding methods can be devised for <a href="/facts/Positional_notation/31DECoN4">other bases</a>, whether positive, negative, fractional, or other elaborations on such themes.
There is no definitive criterion by which any of the representations is universally superior. For integers, the representation used in most current computing devices is two's complement, although the <a href="/facts/UNIVAC_1100%2f2200_series/F4JQVK33">Unisys ClearPath Dorado series</a> mainframes use ones' complement.

Signed number representations open-in-new

Signed number representations