Prime (symbol)
character, used to name a new variable or as an operator denoting derivatives
The prime symbol ′, double prime symbol ″, triple prime symbol ‴, and quadruple prime symbol ⁗ are used to designate units and for other purposes in mathematics, science, linguistics and music.
Although the characters differ little in appearance from those of the apostrophe and single and double quotation marks, the uses of the prime symbol are quite different. While an apostrophe is now often used in place of the prime, and a double quote in place of the double prime (due to the lack of prime symbols on everyday writing keyboards), such substitutions are not considered appropriate in formal materials or in typesetting.
Designation of units
The prime symbol ′ is commonly used to represent feet (ft), and the double prime ″ is used to represent inches (in). The triple prime ‴, as used in watchmaking, represents a ligne (1⁄12 of a "French" inch, or pouce, about 2.26 millimetres or 0.089 inches).
Primes are also used for angles. The prime symbol ′ is used for arcminutes (1⁄60 of a degree), and the double prime ″ for arcseconds (1⁄60 of an arcminute). As an angular measurement, 3° 5′ 30″ means 3 degrees, 5 arcminutes and 30 arcseconds. In historical astronomical works, the triple prime was used to denote "thirds" (1⁄60 of an arcsecond) and a quadruple prime ⁗ "fourths" (1⁄60 of a third of arc), but modern usage has replaced this with decimal fractions of an arcsecond.
Primes are sometimes used to indicate minutes, and double primes to indicate seconds of time, as in the John Cage composition 4′33″ (spoken as "four thirty-three"), a composition that lasts exactly 4 minutes 33 seconds.
Begin with the source’s own compact description: “Prime (symbol)” is character, used to name a new variable or as an operator denoting derivatives. The dossier treats that line as a proposition to test through Prime, symbol and character, not as a finished interpretation.
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This entry incorporates text from “Prime (symbol)” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.