magic number

n.1. Any of the numbers, 2, 8, 20, 28, 50, 82, or 126, that represent the number of neutrons or protons in strongly bound and exceptionally stable atomic nuclei.2. Sports The number of wins by a leading team and losses by its closest competitor required in order for the leading team to capture a championship or secure a playoff spot.

magic number

n 1. (General Physics) physics any of the numbers 2, 8, 20, 28, 50, 82, and 126. Nuclides with these numbers of nucleons appear to have greater stability than other nuclides 2. (Chemistry) chem a number of atoms that is particularly stable in certain types of compound that have clusters of the same type of atom

Thesaurus

Noun

magic number - the atomic number of an extra stable strongly bound atomic nucleus: 2, 8, 20, 28, 50, 82 or 126atomic number - the order of an element in Mendeleyev's table of the elements; equal to the number of protons in the nucleus or electrons in the neutral state of an atom of an element

magic number

(jargon, programming)1. In source code, some non-obviousconstant whose value is significant to the operation of aprogram and that is inserted inconspicuously in-line(hard-coded), rather than expanded in by a symbol set by acommented "#define". Magic numbers in this sense are badstyle.

2. A number that encodes critical information used in analgorithm in some opaque way. The classic examples of theseare the numbers used in hash or CRC functions or thecoefficients in a linear congruential generator forpseudorandom numbers. This sense actually predates, andwas ancestral to, the more common sense 1.

3. Special data located at the beginning of a binary datafile to indicate its type to a utility. Under Unix, thesystem and various applications programs (especially thelinker) distinguish between types of executable file bylooking for a magic number. Once upon a time, these magicnumbers were PDP-11 branch instructions that skipped overheader data to the start of executable code; 0407, forexample, was octal for "branch 16 bytes relative". Nowadaysonly a wizard knows the spells to create magic numbers. MS DOS executables begin with the magic string "MZ".

*The* magic number, on the other hand, is 7+/-2. The papercited below established the number of distinct items (such asnumeric digits) that humans can hold in short-term memory.Among other things, this strongly influenced the interfacedesign of the phone system.

["The magical number seven, plus or minus two: some limits onour capacity for processing information", George Miller, inthe "Psychological Review" 63:81-97, 1956].

magic number

In programming, a magic number is a constant value used to identify a file format, protocol or error code. In many file formats, the first few bytes identify the file; for example, "PK" in ZIP files and the hex values "F8 D8" in JPEG files.

Certain communications protocols use a magic number, such as the hex values "63 82 53 63" at the start of every DHCP packet or "FF 53 4D 42" at the beginning of every SMB request. See DHCP and SMB.

Magic Constants
The term also refers to fixed values in a program that are never expected to change. For example, an algorithm involving playing cards might frequently use the magic constant "52" without jokers or "54" with jokers (or "51" and "53" for offset addresses).

magic number

magic number

magic number

magic number

magic number

magic number

Magic Number

magic number

Words related to magic number

noun the atomic number of an extra stable strongly bound atomic nucleus: 2, 8, 20, 28, 50, 82 or 126

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