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Magic number (programming)
In computer programming, a magic number or magic constant is a numeric literal in source code whose meaning is unclear to the reader. The term is also used outside of programming to refer to a number whose meaning is not obvious without additional knowledge — for example, some file formats are identified by an embedded magic number in the file (see list of file signatures). Also, a number that is relatively uniquely associated with a particular concept, such as a universally unique identifier, might be classified as a magic number.