nichtdecimal

Nichtdecimal is a term used in German-language technical writing to denote numeral representations or systems that are not based on decimal (base-10). As a neologism, its exact scope varies by author, but it is commonly used to refer to non-decimal numeral systems and notations, including binary, octal, hexadecimal, as well as historical bases such as duodecimal (base-12) or sexagesimal (base-60).

In computing and digital contexts, nichtdecimal representations appear in code and data: for example 1011 in binary (base-2) equals 11 in decimal, and FF in hexadecimal (base-16) equals 255 decimal. In other disciplines, nichtdecimal discussions cover the rules of base conversion, notation conventions, and the historical use of alternative bases.

Because nichtdecimal is not a formal standard, its precise meaning can depend on the author or field. Some sources treat it as synonymous with any non-base-10 numeral system, while others limit it to positional systems that use a base other than ten.

See also: non-decimal numeral systems; base conversion; numeral systems.