Percent sign explained

Mark:	%
Percent sign
See Also:	(Basis point)
Different From:

The percent sign (sometimes per cent sign in British English) is the symbol used to indicate a percentage, a number or ratio as a fraction of 100. Related signs include the permille (per thousand) sign and the permyriad (per ten thousand) sign (also known as a basis point), which indicate that a number is divided by one thousand or ten thousand, respectively. Higher proportions use parts-per notation.

Correct style

Form and spacing

English style guides prescribe writing the percent sign following the number without any space between (e.g. 50%). However, the International System of Units and ISO 31-0 standard prescribe a space between the number and percent sign,^{[1] [2] [3]} in line with the general practice of using a non-breaking space between a numerical value and its corresponding unit of measurement.

Other languages have other rules for spacing in front of the percent sign:

• In Czech and in Slovak, the percent sign is spaced with a non-breaking space if the number is used as a noun.^[4] In Czech, no space is inserted if the number is used as an adjective (e.g. "a 50% increase"),^[5] whereas Slovak uses a non-breaking space in this case as well.^[6]
• In Croatian, the percent sign is spaced^[7] with a non-breaking space.
• In Finnish, the percent sign is always spaced, and a case suffix can be attached to it using the colon (e.g. 50 %:n kasvu 'an increase of 50%').^[8]
• In French, the percent sign must be spaced with a non-breaking space.^{[9] [10]}
• According to the Real Academia Española, in Spanish, the percent sign should be spaced now, despite the fact that it is not the linguistic norm.^[11] Despite that, in North American Spanish (Mexico and the US), several style guides and institutions either recommend the percent sign be written following the number without any space between or do so in their own publications in accordance with common usage in that region.^{[12] [13]}
• In Russian, the percent sign is rarely spaced, contrary to the guidelines of the GOST 8.417-2002 state standard.
• In Chinese, the percent sign is almost never spaced, probably because Chinese does not use spaces to separate characters or words at all.
• According to the Swedish Language Council, the percent sign should be preceded by a space in Swedish, as all other units.
• In German, the space is prescribed by the regulatory body in the national standard DIN 5008.
• In Turkish and some other Turkic languages, the percent sign precedes rather than follows the number, without an intervening space.
• In Persian texts, the percent sign may either precede or follow the number, in either case without a space.
• In Arabic, the percent sign follows the number; as Arabic is written from right to left, this means that the percent sign is to the left of the number, usually without a space.
• In Hebrew, the percent sign is written to the right of the number, just as in English, without an intervening space. This is because numbers in Hebrew (which otherwise is written from right to left) are written from left to right, as in English.
• In Dutch, the official rule (NBN Z 01-002) is to place a space between the number and the sign (e.g. "een stijging van 50 %"), but most of the time, the space is missing (e.g. "een stijging van 50%").^[14]

Usage in text

It is often recommended that the percent sign only be used in tables and other places with space restrictions. In running text, it should be spelled out as percent or per cent (often in newspapers). For example, not "Sales increased by 24% over 2006" but "Sales increased by 24 percent over 2006".^{[15] [16] [17]}

Evolution

Prior to 1425, there is no known evidence of a special symbol being used for percentages. The Italian term per cento, "for a hundred", was used as well as several different abbreviations (e.g. "per 100", "p 100", "p cento"). Examples of this can be seen in the 1339 arithmetic text (author unknown) depicted below. The letter p with its descender crossed by a horizontal or diagonal stroke (to indicate abbreviation) conventionally stood for per, por, par, or pur in Medieval and Renaissance palaeography.^[18]

At some point, a scribe used the abbreviation pc with a tiny loop or circle (depicting the ending -o used in Italian ordinals, as in primo, secondo; it is analogous to the English -th as in 25th). This appears in some additional pages of a 1425 text which were probably added around 1435.

The pc with a loop eventually evolved into a horizontal fraction sign by 1650 (see below for an example in a 1684 text) and thereafter lost the per.

In 1925, D. E. Smith wrote, "The solidus form is modern."

Encodings

Unicode

The Unicode code points are:

• (HTML %, %^[19]),
  • • , which has the circles replaced by square dots set on edge, the shape of the digit 0 in Eastern Arabic numerals.
• , Japanese: パーセント (from English "percent") in one square character.

ASCII

The ASCII code for the percent character is 37, or 0x25 in hexadecimal.

Other uses

In computers

Names for the percent sign include percent sign (in ITU-T), mod, grapes (in hacker jargon), and the humorous double-oh-seven (in INTERCAL).

In computing, the percent character is also used for the modulo operation in programming languages that derive their syntax from the C programming language, which in turn acquired this usage from the earlier B.^[20]

In the textual representation of URIs, a % immediately followed by a 2-digit hexadecimal number denotes an octet specifying (part of) a character that might otherwise not be allowed in URIs (see percent-encoding).

In SQL, the percent sign is a wildcard character in "LIKE" expressions, for example will fetch all records whose names start with "".

In TeX (and therefore also in LaTeX) and PostScript, and in GNU Octave and MATLAB,^[21] a % denotes a line comment.

In BASIC, Visual Basic, ASP, and VBA a trailing % after a variable name marks it as an integer.

In ASP, the percent sign can be used to indicate the start and end of the ASP code

In Perl % is the sigil for hashes.

In many programming languages' string formatting operations (performed by functions such as [[printf]] and [[scanf]]), the percent sign denotes parts of the template string that will be replaced with arguments. (See printf format string.) In Python and Ruby the percent sign is also used as the string formatting operator.^{[22] [23] [24]}

In the command processors COMMAND.COM (DOS) and CMD.EXE (OS/2 and Windows),,... stand for the first, second,... parameters of a batch file. %0 stands for the specification of the batch file itself as typed on the command line. The % sign is also used similarly in the FOR command.%VAR1% represents the value of an environment variable named VAR1. Thus:sets a new value for PATH, that being the old value preceded by "c:\;".Because these uses give the percent sign special meaning, the sequence %% (two percent signs) is used to represent a literal percent sign, so that:would set PATH to the literal value "c:\;%PATH%".

In the C Shell, % is part of the default command prompt.

In linguistics

In linguistics, the percent sign is prepended to an example sentence or other string to show that it is judged well-formed (grammatical) by some speakers and ill-formed by others. This may be due to differences in dialect or even individual idiolects.^{[25] [26]} This use is similar to those of the asterisk to mark ill-formed strings, the question mark to mark strings where well-formedness is unclear, and the number sign to mark strings that are syntactically well-formed but semantically or pragmatically nonsensical.

See also

• Metacharacter
• ,
• (also known as basis point)

Notes and References

1. Web site: SI Brochure . . 2006 . 2016-05-05 . 21 March 2019 . https://web.archive.org/web/20190321011300/https://www.bipm.org/en/publications/si-brochure/section5-3-7.html . live .
2. Web site: The International System of Units . . 2006 . 2007-08-06 . 13 March 2020 . https://web.archive.org/web/20200313143915/https://www.bipm.org/utils/common/pdf/si_brochure_8.pdf . live .
3. Web site: Quantities and units – Part 0: General principles . . 1999-12-22 . 2007-01-05 . 29 May 2007 . https://web.archive.org/web/20070529115226/http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=3621 . live .
4. Web site: Internetová jazyková příručka . . 2014 . 2014-11-24 . 14 February 2015 . https://web.archive.org/web/20150214110059/http://prirucka.ujc.cas.cz/?id=880 . live .
5. Web site: Jazyková poradna ÚJČ AV ČR: FAQ . . 2002 . 2009-03-16 . dead . https://web.archive.org/web/20020419163402/http://www.ujc.cas.cz/poradna/odpo.html#12st . 2002-04-19.
6. Web site: Jazyková poradňa . . 2013 . 2019-10-26 . https://web.archive.org/web/20090221135605/http://www.ujc.cas.cz/poradna/odpo.html#12st . 2009-02-21 . dead.
7. Web site: Znak za postotak . . hr.
8. Web site: Kielikello 2/2006 . Kotimaisten kielten keskus . kotus.fi . 2006 . 2015-06-30 . 1 May 2015 . https://web.archive.org/web/20150501222450/http://www.kielikello.fi/index.php?mid=2&pid=11&aid=1696 . live .
9. Book: Guide des principales règles typographiques. Université Joseph-Fourier. 8 June 2022.
10. Book: André, Jacques . Petites leçons de typographie . Rennes . . 34 . 8 June 2022 .
11. Web site: El % se escribe separado de la cifra a la que acompaña . Fundeu . fundeu.es . 2012 . 2021-11-24 . 24 November 2021 . https://web.archive.org/web/20211124144146/https://www.fundeu.es/recomendacion/el-se-escribe-separado-de-la-cifra-a-la-que-acompana-802/ . live .
12. Web site: Normas particulares de estilo . Colegio de México . colmex.mx . 2020 . 2022-04-05 . 10 May 2022 . https://web.archive.org/web/20220510021038/https://estudiosdegenero.colmex.mx/index.php/eg/normas_estilo#:~:text=Porcentajes.,detr%C3%A1s%20de%20la%20%C3%BAltima%20cifra . live .
13. Web site: ¿En un texto, es correcto usar el signo de porcentaje o tiene que escribirse por ciento? . Academia Mexicana de la Lengua . academia.org.mx . 2020 . 2022-04-05 . 6 February 2023 . https://web.archive.org/web/20230206061748/https://www.academia.org.mx/consultas/consultas-frecuentes/item/porcentaje . live .
14. Web site: procentteken (spatie). 2021-11-27. www.vlaanderen.be. nl.
15. Web site: American Economic Review: Style Guide . dead . https://web.archive.org/web/20071225140441/http://www.aeaweb.org/aer/styleguide.html . 2007-12-25 .
16. Web site: UNC Pharmacy style guide . 16 October 2007 . 12 June 2007 . https://web.archive.org/web/20070612101024/http://www.pharmacy.unc.edu/news/communications-office/style-guide . dead .
17. Web site: University of Colorado style guide . 2007-10-16 . https://web.archive.org/web/20071102153519/http://www.colorado.edu/Publications/styleguide/numbers.html . 2007-11-02 . dead .
18. http://inkunabeln.ub.uni-koeln.de/vdibProduction/handapparat/nachs_w/cappelli/capp317.html Letter p.
19. HTML5 is the only version of HTML that has a named entity for the percent sign, see https://www.w3.org/TR/html4/sgml/entities.html ("The following sections present the complete lists of character entity references.") and https://www.w3.org/TR/2014/CR-html5-20140731/syntax.html#named-character-references ("percnt;").
20. Web site: Users' Reference to B . Ken . Thompson . 1996 . dead . https://web.archive.org/web/20060706005453/http://cm.bell-labs.com/cm/cs/who/dmr/kbman.html . 2006-07-06 .
21. Web site: 2.7.1 Single Line Comments. GNU. 20 July 2018.
22. Web site: Python 2 – String Formatting Operations. 28 October 2015.
23. Web site: Python 3 – printf-style String Formatting. 28 October 2015.
24. Web site: Ruby – String#%. 28 October 2015.
25. Book: Trask, R. L. . Larry Trask . A Dictionary of Grammatical Terms in Linguistics . London . Routledge . 1993 . 0-415-08627-2 . 203.
26. Book: Crystal, David . David Crystal . A Dictionary of Linguistics and Phonetics . 6th . Cambridge . Cambridge University Press . 2008 . 978-1-4051-5296-9 . 355.