# Prime (symbol)

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The prime symbol, double prime symbol (″), triple prime symbol (‴), quadruple prime symbol (⁗) etc., are used to designate units and for other purposes in mathematics, the sciences, linguistics and music.wikipedia
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### Apostrophe

apostrophespossessive apostrophe
Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent, or grave accent ; the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe .
(When it functions as a closing quotation mark, it is always paired with an opening quotation mark.) The apostrophe also looks similar to, but is not the same as, the prime symbol, which is used to indicate measurement in feet or arcminutes, as well as for various mathematical purposes, and the ʻokina, which represents a glottal stop in Polynesian languages.

### Foot (unit)

feetftfoot
The prime symbol is commonly used to represent feet (ft) and arcminutes (arcmin).
The foot ( pl. feet; abbreviation: ft; symbol: ′, the prime symbol) is a unit of length in the imperial and US customary systems of measurement.

### Quotation mark

quotation marksdouble quotes
Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent, or grave accent ; the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe .
The closing single quotation mark is identical or similar in form (depending on the font) to the apostrophe and similar to the prime symbol.

### Inch

ininchesinternational inch
The double prime represents inches (in) and arcseconds (arcsec).
The inch (abbreviation: in or ″) is a unit of length in the (British) imperial and United States customary systems of measurement.

### Minute and second of arc

masarcsecondarc second
The prime symbol is commonly used to represent feet (ft) and arcminutes (arcmin). The double prime represents inches (in) and arcseconds (arcsec). As an angular measurement, 3° 5′ 30″ means 3 degrees, 5 arcminutes and 30 arcseconds.
The standard symbol for marking the arcminute is the prime (U+2032), though a single quote (U+0027) is commonly used where only ASCII characters are permitted.

### Ligne

ligneslinesParis line
The triple prime (‴) in watchmaking represents a ligne or 1/12 of an inch.
The standardized conversion for a ligne is 2.2558291 mm (1 mm = 0.443296 ligne), and it is abbreviated with the letter L or represented by the triple prime, ‴.

### Degree (angle)

°degreesdegree
As an angular measurement, 3° 5′ 30″ means 3 degrees, 5 arcminutes and 30 arcseconds.
These subdivisions, also called the arcminute and arcsecond, are respectively represented by a single and double prime.

### X-bar theory

X-bar schemaX-barX-bar framework
Originally, X-bar theory used a bar over syntactic units to indicate bar-levels in syntactic structure, generally rendered as an overbar.
Because this may be difficult to typeset, this is often written as X′, using the prime symbol or with superscript numerals as exponents, e.g., X 1 . In English, however, this is still read as "X bar".

### Derivative

differentiationdifferentiablefirst derivative
A derivative or differentiated function: f′(x) and f″(x) are the first and second derivatives of f(x) with respect to x. Likewise are f‴(x) and f⁗(x) . Similarly, if y = f(x) then y′ and y″ are the first and second derivatives of y with respect to x. (Other notation exists)
Sometimes referred to as prime notation, one of the most common modern notation for differentiation is due to Joseph-Louis Lagrange and uses the prime mark, so that the derivative of a function f is denoted f'. Similarly, the second and third derivatives are denoted

### Helmholtz pitch notation

HelmholtzAA-f 3 AAA–c&prime;&prime;&prime;&prime;&prime;
The prime symbol is used in combination with lower case letters in the Helmholtz pitch notation system to distinguish notes in different octaves from middle C upwards.
Developed by the German scientist Hermann von Helmholtz, it uses a combination of upper and lower case letters (A to G), and the sub- and super-prime symbols to describe each individual note of the scale.

### Rubik's Cube

3x3x3Rubik's Cubesrubix cube
In Rubik's Cube move notation the prime is used to invert moves or move sequences (e.g., L means "turn the left face 90 degrees clockwise", whereas L′ means "turn the left face 90 degrees counter-clockwise").
When a prime symbol follows a letter, it denotes an anticlockwise face turn; while a letter without a prime symbol denotes a clockwise turn.

### Soft sign

ЬЬ ьsoft
Prime and double prime are used to transliterate Cyrillic yeri (the soft sign, ь) and yer (the hard sign, ъ).
In the romanization of Cyrillic words, soft signs are typically replaced with the prime symbol ′.

### Overline

overbarbarcombining overline
Originally, X-bar theory used a bar over syntactic units to indicate bar-levels in syntactic structure, generally rendered as an overbar.
Due to difficulty in typesetting the overbar, the prime symbol is often used instead, as in X′. Contemporary typesetting software, such as LaTeX, has made typesetting overbars considerably simpler; both prime and overbar markers are accepted usages.

### Typewriter

typewriterselectric typewritertypewritten
* Typewriter conventions
Other examples of typewriter practices that are sometimes still used in desktop publishing systems include inserting a double space at the end of a sentence, and the use of straight quotes (or "dumb quotes") as quotation marks and prime marks.

### List of XML and HTML character entity references

character entity referenceHTML entitycharacter entity

### Stress (linguistics)

stressstressedunstressed
The "modifier letter prime" and "modifier letter double prime" characters are intended for linguistic purposes, such as the indication of stress or the transliteration of certain Cyrillic characters.
In English dictionaries that show pronunciation by respelling, stress is typically marked with a prime mark placed after the stressed syllable: /si-lab′-ə-fi-kay′-shən/.

### Mathematics

mathematicalmathmathematician
The prime symbol, double prime symbol (″), triple prime symbol (‴), quadruple prime symbol (⁗) etc., are used to designate units and for other purposes in mathematics, the sciences, linguistics and music.

### Linguistics

linguistlinguisticlinguists
The prime symbol, double prime symbol (″), triple prime symbol (‴), quadruple prime symbol (⁗) etc., are used to designate units and for other purposes in mathematics, the sciences, linguistics and music.

### Music

audiomusicalPop
The prime symbol, double prime symbol (″), triple prime symbol (‴), quadruple prime symbol (⁗) etc., are used to designate units and for other purposes in mathematics, the sciences, linguistics and music.

### Acute accent

Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent, or grave accent ; the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe .

### Grave accent

graveùbackquote
Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent, or grave accent ; the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe .

### Ditto mark

Ditto '''″''' '''″''' Ditto
Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent, or grave accent ; the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe .

### Modifier letter double apostrophe

ˮdouble apostropheletter double apostrophe
Although similar in appearance, the prime symbol should not be confused with the apostrophe (’ or '), single quotation mark (' or ‘ or ’), acute accent, or grave accent ; the double prime symbol should not be confused with the double quotation mark (“…” or "…"), the ditto mark (”), or the letter double apostrophe .

### Geresh

The prime symbol is very similar to the Hebrew geresh, but in modern fonts the geresh is designed to be aligned with the Hebrew letters and the prime symbol is not, so they should not be interchanged.

### Watchmaker

watchmakingwatchmakerswatch-maker
The triple prime (‴) in watchmaking represents a ligne or 1/12 of an inch.