Percent sign
Encyclopedia
The percent sign is the symbol used to indicate a percentage
(that the preceding number is divided by one hundred).
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
.
that there should be a space, whilst others advise against it. The brochure of the International System of Units
declares in chapter 5: “a space separates the number and the symbol %”.
The ISO 31-0
standard also specifies a space. This is in accordance with the general rule of adding a non-breaking space
between a numerical value and its corresponding unit of measurement. However, style guides—such as the Chicago Manual of Style
—commonly prescribe to write the number and percent sign without any space in between.
In some languages, however, there are specific rules of spacing in front of the percent sign. In Czech
, for example, the percent sign is spaced if the number is used as a noun, while no space is inserted if the number is used as an adjective (e.g. “a 50% increase”). 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 %'). In French
, the percent sign is also always spaced because the percent is considered as a unit. In traditional Russian typography there is a set rule to space it by 3 pt but it is not that common in Russia today. 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
.
term per cento, "for a hundred", was used as well as several different abbreviations (e.g. "per 100", "p 100", "p cento", etc.). Examples of this can be seen in the 1339 arithmetic text (author unknown) depicted below.
At some point a scribe of some sort used the abbreviation "pc" with a tiny loop (small circle used in Italian numeration for primo, secondo, etc.) This appears in some additional pages of a 1425 text which were probably added around 1435. This is shown below (source, Rara Arithmetica pg. 440).
The "pc" with a loop eventually evolved 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."
and
There is also , which has the circles replaced by square dots set on edge.
The ASCII code for the percent character
is 37, or 0x25 in hexadecimal
.
), 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 language
s that derive their syntax from the C programming language
, which in turn acquired this usage from the earlier B.
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
In TeX
(and therefore also in LaTeX) and PostScript
, a % denotes a line comment.
In BASIC
, a trailing % after a variable name marks it as an integer
.
In Perl
% is the sigil
for hashes
.
In many programming languages' string formatting operations (performed by functions such as printf
) the percent sign denotes parts of the template string that will be replaced with arguments. In Python
(obsoleted in 3.0) and Ruby
, the percent sign is also used as the string formatting operator.
In the command processors COMMAND.COM
(DOS) and CMD.EXE
(OS/2 and Windows), %1, %2,... 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:
set PATH=c:\;%PATH%
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:
set PATH=c:\;%%PATH%%
would set PATH to the literal value "c:\;%PATH%".
In the C Shell
, % is part of the default command prompt.
to show that it is judged well-formed
by some speakers and ill-formed by others. This may be due to differences in dialect
or even individual idiolect
s. This is similar to 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 nonsensical.
Percentage
In mathematics, a percentage is a way of expressing a number as a fraction of 100 . It is often denoted using the percent sign, “%”, or the abbreviation “pct”. For example, 45% is equal to 45/100, or 0.45.Percentages are used to express how large/small one quantity is, relative to another quantity...
(that the preceding number is divided by one hundred).
Related signs include the permille
Permille
A per mil or per mille is a tenth of a percent or one part per thousand. It is written with the sign ‰ , which looks like a percent sign with an extra zero at the end...
(per thousand) sign ‰ and the permyriad (per ten thousand) sign (also known as a basis point
Basis point
A basis point is a unit equal to 1/100 of a percentage point or one part per ten thousand...
), which indicate that a number is divided by one thousand or ten thousand respectively. Higher proportions use parts-per notation
Parts-per notation
In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement...
.
Spacing
There is no consensus as to whether or not to include a space between the number and percent sign in English. Many authorities prescribeLinguistic prescription
In linguistics, prescription denotes normative practices on such aspects of language use as spelling, grammar, pronunciation, and syntax. It includes judgments on what usages are socially proper and politically correct...
that there should be a space, whilst others advise against it. The brochure of the International System of Units
International System of Units
The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...
declares in chapter 5: “a space separates the number and the symbol %”.
The ISO 31-0
ISO 31-0
ISO 31-0 is the introductory part of international standard ISO 31 on quantities and units. It provides guidelines for using physical quantities, quantity and unit symbols, and coherent unit systems, especially the SI...
standard also specifies a space. This is in accordance with the general rule of adding a non-breaking space
Non-breaking space
In computer-based text processing and digital typesetting, a non-breaking space or no-break space is a variant of the space character that prevents an automatic line break at its position. In certain formats , it also prevents the “collapsing” of multiple consecutive whitespace characters into a...
between a numerical value and its corresponding unit of measurement. However, style guides—such as the Chicago Manual of Style
The Chicago Manual of Style
The Chicago Manual of Style is a style guide for American English published since 1906 by the University of Chicago Press. Its 16 editions have prescribed writing and citation styles widely used in publishing...
—commonly prescribe to write the number and percent sign without any space in between.
In some languages, however, there are specific rules of spacing in front of the percent sign. In Czech
Czech language
Czech is a West Slavic language with about 12 million native speakers; it is the majority language in the Czech Republic and spoken by Czechs worldwide. The language was known as Bohemian in English until the late 19th century...
, for example, the percent sign is spaced if the number is used as a noun, while no space is inserted if the number is used as an adjective (e.g. “a 50% increase”). In Finnish
Finnish language
Finnish is the language spoken by the majority of the population in Finland Primarily for use by restaurant menus and by ethnic Finns outside Finland. It is one of the two official languages of Finland and an official minority language in Sweden. In Sweden, both standard Finnish and Meänkieli, a...
, the percent sign is always spaced, and a case suffix
Finnish language noun cases
Finnish nouns as well as any modifying adjectives, superlatives or comparatives, can be declined by a large number of grammatical cases, which are detailed here. See also Finnish grammar....
can be attached to it using the colon
Colon (punctuation)
The colon is a punctuation mark consisting of two equally sized dots centered on the same vertical line.-Usage:A colon informs the reader that what follows the mark proves, explains, or lists elements of what preceded the mark....
(e.g. 50 %:n kasvu 'an increase of 50 %'). In French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
, the percent sign is also always spaced because the percent is considered as a unit. In traditional Russian typography there is a set rule to space it by 3 pt but it is not that common in Russia today. In Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...
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
Swedish Language Council
The Swedish Language Council is the primary regulatory body for the advancement and cultivation of the Swedish language. The council is partially funded by the Swedish government and has semi-official status...
, the percent sign should be preceded by a space in Swedish
Swedish language
Swedish is a North Germanic language, spoken by approximately 10 million people, predominantly in Sweden and parts of Finland, especially along its coast and on the Åland islands. It is largely mutually intelligible with Norwegian and Danish...
.
Usage in text
It is often recommended that the percent sign is only 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 rather "Sales increased by 24 percent over 2006".Evolution
Prior to 1425 there is no evidence of a special symbol being used for percentage. The ItalianItalian language
Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...
term per cento, "for a hundred", was used as well as several different abbreviations (e.g. "per 100", "p 100", "p cento", etc.). Examples of this can be seen in the 1339 arithmetic text (author unknown) depicted below.
At some point a scribe of some sort used the abbreviation "pc" with a tiny loop (small circle used in Italian numeration for primo, secondo, etc.) This appears in some additional pages of a 1425 text which were probably added around 1435. This is shown below (source, Rara Arithmetica pg. 440).
The "pc" with a loop eventually evolved 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
Solidus (punctuation)
The solidus is a punctuation mark used to indicate fractions including fractional currency. It may also be called a shilling mark, an in-line fraction bar, or a fraction slash....
form is modern."
Encodings
The Unicode code points are ,and
There is also , which has the circles replaced by square dots set on edge.
The ASCII code for the percent character
Character (computing)
In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....
is 37, or 0x25 in hexadecimal
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
.
In computers
Names for the percent sign include percent sign (in ITU-TITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
), mod
Modulo operation
In computing, the modulo operation finds the remainder of division of one number by another.Given two positive numbers, and , a modulo n can be thought of as the remainder, on division of a by n...
, grapes (in hacker jargon
Jargon
Jargon is terminology which is especially defined in relationship to a specific activity, profession, group, or event. The philosophe Condillac observed in 1782 that "Every science requires a special language because every science has its own ideas." As a rationalist member of the Enlightenment he...
), and the humorous double-oh-seven (in INTERCAL
INTERCAL
INTERCAL, a programming language parody, is an esoteric programming language that was created by Don Woods and James M. Lyon, two Princeton University students, in 1972. It satirizes aspects of the various programming languages at the time, as well as the proliferation of proposed language...
).
In computing
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, the percent character
Character (computing)
In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language....
is also used for the modulo operation
Modulo operation
In computing, the modulo operation finds the remainder of division of one number by another.Given two positive numbers, and , a modulo n can be thought of as the remainder, on division of a by n...
in programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s that derive their syntax from the C programming language
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, which in turn acquired this usage from the earlier B.
In the textual representation of URIs
Uniform Resource Identifier
In computing, a uniform resource identifier is a string of characters used to identify a name or a resource on the Internet. Such identification enables interaction with representations of the resource over a network using specific protocols...
, a % immediately followed by a 2-digit hexadecimal
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
number denotes an octet specifying (part of) a character that might otherwise not be allowed in URIs (see percent-encoding
Percent-encoding
Percent-encoding, also known as URL encoding, is a mechanism for encoding information in a Uniform Resource Identifier under certain circumstances. Although it is known as URL encoding it is, in fact, used more generally within the main Uniform Resource Identifier set, which includes both Uniform...
).
In SQL
SQL
SQL is a programming language designed for managing data in relational database management systems ....
, the percent sign is a wildcard character
Wildcard character
-Telecommunication:In telecommunications, a wildcard character is a character that may be substituted for any of a defined subset of all possible characters....
in "LIKE" expressions, for example
SELECT * FROM table WHERE fullname LIKE 'Lisa %' will fetch all records whose names start with "Lisa "In TeX
TeX
TeX is a typesetting system designed and mostly written by Donald Knuth and released in 1978. Within the typesetting system, its name is formatted as ....
(and therefore also in LaTeX) and PostScript
PostScript
PostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
, a % denotes a line comment.
In BASIC
BASIC
BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
, a trailing % after a variable name marks it as an integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...
.
In Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
% is the sigil
Sigil (computer programming)
In computer programming, a sigil is a symbol attached to a variable name, showing the variable's datatype or scope. In 1999 Philip Gwyn adopted the term "to mean the funny character at the front of a Perl variable".- Historical context:...
for hashes
Hash table
In computer science, a hash table or hash map is a data structure that uses a hash function to map identifying values, known as keys , to their associated values . Thus, a hash table implements an associative array...
.
In many programming languages' string formatting operations (performed by functions such as printf
Printf
Printf format string refers to a control parameter used by a class of functions typically associated with some types of programming languages. The format string specifies a method for rendering an arbitrary number of varied data type parameter into a string...
) the percent sign denotes parts of the template string that will be replaced with arguments. In Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
(obsoleted in 3.0) and Ruby
Ruby (programming language)
Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro "Matz" Matsumoto...
, the percent sign is also used as the string formatting operator.
In the command processors COMMAND.COM
COMMAND.COM
COMMAND.COM is the filename of the default operating system shell for DOS operating systems and the default command line interpreter on Windows 95, Windows 98 and Windows Me...
(DOS) and CMD.EXE
Cmd.exe
Command Prompt is the Microsoft-supplied command-line interpreter on OS/2, Windows CE and on Windows NT-based operating systems...
(OS/2 and Windows), %1, %2,... stand for the first, second,... parameters of a batch file
Batch file
In DOS, OS/2, and Microsoft Windows, batch file is the name given to a type of script file, a text file containing a series of commands to be executed by the command interpreter....
. %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
Environment variable
Environment variables are a set of dynamic named values that can affect the way running processes will behave on a computer.They can be said in some sense to create the operating environment in which a process runs...
named VAR1. Thus:
set PATH=c:\;%PATH%
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:
set PATH=c:\;%%PATH%%
would set PATH to the literal value "c:\;%PATH%".
In the C Shell
C shell
The C shell is a Unix shell that was created by Bill Joy while a graduate student at University of California, Berkeley in the late 1970s. It has been distributed widely, beginning with the 2BSD release of the BSD Unix system that Joy began distributing in 1978...
, % is part of the default command prompt.
In linguistics
In linguistics, the percent sign is prepended to an example stringString (computer science)
In formal languages, which are used in mathematical logic and theoretical computer science, a string is a finite sequence of symbols that are chosen from a set or alphabet....
to show that it is judged well-formed
Well-formed
Well-formed may refer to:* Well-formed element, an element in webpage design; see also well-formed XML* Well-formed formula, a string that is generated by a formal grammar in logic* Well-formed outcome, a Neuro-Linguistic Programming concept...
by some speakers and ill-formed by others. This may be due to differences in dialect
Dialect
The term dialect is used in two distinct ways, even by linguists. One usage refers to a variety of a language that is a characteristic of a particular group of the language's speakers. The term is applied most often to regional speech patterns, but a dialect may also be defined by other factors,...
or even individual idiolect
Idiolect
In linguistics, an idiolect is a variety of a language unique to an individual. It is manifested by patterns of vocabulary or idiom selection , grammar, or pronunciations that are unique to the individual. Every individual's language production is in some sense unique...
s. This is similar to the asterisk
Asterisk
An asterisk is a typographical symbol or glyph. It is so called because it resembles a conventional image of a star. Computer scientists and mathematicians often pronounce it as star...
to mark ill-formed strings, the question mark
Question mark
The question mark , is a punctuation mark that replaces the full stop at the end of an interrogative sentence in English and many other languages. The question mark is not used for indirect questions...
to mark strings where well-formedness is unclear, and the number sign
Number sign
Number sign is a name for the symbol #, which is used for a variety of purposes including, in some countries, the designation of a number...
to mark strings that are syntactically well-formed but semantically nonsensical.