ವಿಕಿಪೀಡಿಯ:Manual of Style/Dates and numbers: ಪರಿಷ್ಕರಣೆಗಳ ನಡುವಿನ ವ್ಯತ್ಯಾಸ

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This part of the '''[[Wikipedia:Manual of Style|Manual of Style]]''' helps editors to achieve consistency in the use and formatting of numbers, dates, times, measurements, currencies, and coordinates in Wikipedia articles. Consistency in style and formatting promotes clarity and cohesion; this is especially important within an article. The goal is to make the whole encyclopedia easier and more intuitive to use. Try to write so the text cannot be misunderstood, and take account of what is likely to be familiar to readers. The less that readers have to look up definitions, the easier the text will be to understand.

Where this manual provides options, consistency should be maintained within an article unless there is a good reason to do otherwise. The [[Wikipedia:Arbitration Committee|Arbitration Committee]] has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style, and that revert-warring over optional styles is unacceptable.<ref>{{section link|Wikipedia:Requests for arbitration/Jguk|Principles}}, {{section link|Wikipedia:Requests for arbitration/jguk 2|Principles}}, and {{section link|Wikipedia:Requests for arbitration/Sortan|Principles}}</ref> If discussion cannot determine which style to use in an article, defer to the style used by the first major contributor.

Quotations, titles of books and articles, and similar "imported" text should be faithfully reproduced, even if they employ formats or units inconsistent with these guidelines or with other formats in the same article. If necessary, clarify via ''[bracketed interpolation]'', article text, or footnotes.

* It is acceptable to change other date formats in the same article to provide consistency, so long as those changes would otherwise be acceptable.<!-- "to provide consistency" with what? Is this suggesting changing the article to match a quote or quotes?-->

===Non-breaking spaces===

Guidance on the use of [[non-breaking space]]s (also called "hard spaces"; ''markup:'' <code>{{t|nbsp}}</code> or <code>&amp;nbsp;</code>) is given in some of the sections below, though not all situations in which ''nbsp'' may be appropriate are described. {{t|nowrap}} may also be useful in some situations. For further information see {{section link|Wikipedia:Manual of Style|Non-breaking spaces}} and [[Wikipedia:Line-break handling]].

==Chronological items==

<!-- {{Split section|Manual of Style (time and dates)|discuss=Wikipedia Talk:Manual of Style (dates and numbers)#Split proposal}} -->

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===<span id="Precise language" />Statements likely to become outdated===

{{Shortcut|WP:DATED|WP:EPHEMERAL}}

{{See also|Wikipedia:As of|Wikipedia:Manual of Style/Words to watch#Relative time references}}

Except on pages updated regularly (e.g. [[Wikipedia:How the Current events page works|current events]]), terms such as {{!xt|now}}, {{!xt|soon}}, {{!xt|currently}}, and {{!xt|recently}} should usually be avoided in favor of phrases such as {{xt|during the 1990s}} and {{xt|in August 1969}}. For future and current events, use phrases such as {{xt|as of {{CURRENTMONTHNAME}} {{CURRENTYEAR}}}} or {{xt|since the beginning of 2010}} to signal the time-dependence of the information. Or (for example) {{tlc|as of|{{CURRENTYEAR}}}} will produce the text {{xt|{{as of|{{CURRENTYEAR}}}}}} and adds the article to a category flagging it for periodic review.<!--though of course this will never happen--> However, do not replace (for example) {{xt|since the start of 2005}} with {{tlc|as of|2005}} because some information (the ''start'' of 2005) would be lost; advanced features of {{tlf|as of}} such as <code><nowiki>{{as of|2005|alt=since the start of 2005}}</nowiki></code> can be used in such circumstances.

Relative-time expressions are acceptable for very long periods, such as geological epochs: {{xt|Humans diverged from apes long ago, but [[wikiquote:Samuel Butler (novelist)#Miscellaneous|only recently developed state legislatures]].}}

===Time of day===

{{Shortcut|WP:MOSTIME|MOS:TIME}}

* '''12-hour clock times''' end with dotted or undotted lower-case ''a.m.'' or ''p.m.'', or ''am'' or ''pm'', preceded by a space (e.g. {{xt|2:30{{nbsp}}p.m.}} or {{xt|2:30{{nbsp}}pm}}, not {{!xt|2:30p.m.}} or {{!xt|2:30pm}}). Hours denoted by a single digit should not have a leading zero (e.g. {{xt|2:30{{nbsp}}p.m.}}, not {{!xt|02:30{{nbsp}}p.m.}}). A hard space (see [[#Non-breaking spaces|above]]) is advisable (<code>2:30&amp;nbsp;pm</code> or {{tlx|nowrap|2:30 p.m.}}). Use {{xt|noon}} and {{xt|midnight}} rather than {{!xt|12 pm}} and {{!xt|12 am}}; whether ''midnight'' refers to the start or the end of a date will need to be specified unless it is clear from the context.

* '''24-hour clock times''' have no a.m., p.m., noon or midnight suffix. Hours under 10 should have a leading zero (e.g. {{xt|08:15}}). {{xt|00:00}} refers to midnight at the start of a date, {{xt|12:00}} to noon, and {{xt|24:00}} to midnight at the end of a date, but "24" should not be used for the first hour of the next day (e.g. use {{xt|00:10}} for ten minutes after midnight, not {{!xt|24:10}}).

The numerical elements of times-of-day are figures ({{xt|12:45{{nbsp}}p.m.}}) rather than words ({{!xt|twelve forty-five p.m.}}) though conventional terms such as {{xt|noon}} and {{xt|midnight}} are acceptable (taking care, with the latter, to avoid possible date ambiguity in constructions such as ''midnight on July 17'').

====<span id="timezones" />Time zones====

{{shortcut|WP:TIMEZONE}}Give dates and times appropriate to the [[time zone]] where an event took place. For example, the date of the [[attack on Pearl Harbor]] should be December{{nbsp}}7, 1941 (Hawaii time/{{zwsp}}date). Give priority to the place at which the event had its most significant effects; for example, if a hacker based in Japan attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. In some cases the best solution may be to add the date and time in [[Coordinated Universal Time]] (UTC). For example:

:{{in5|2}}&bull;{{in5|2}} {{xt|8{{nbsp}}p.m. [[Eastern Standard Time (North America)|Eastern Standard Time]] on January{{nbsp}}15, 2001 (01:00{{nbsp}}UTC, January{{nbsp}}16)}}

Alternatively, include just the [[UTC offset]]:

:{{in5|2}}&bull;{{in5|2}}{{xt|21:00{{nbsp}}[[British Summer Time]] ([[UTC+1]]) on 27{{nbsp}}July 2012}}

Rarely, the time zone in which a historical event took place has since changed; for example, China to 1949 was divided into [[Historical time zones of China|five time zones]], whereas all of modern China is [[UTC+8]]. Similarly, the term "UTC" is not appropriate for dates before this system was adopted in 1961; [[Universal Time]] (UT) is the appropriate term for the mean time at the [[prime meridian (Greenwich)]] when it is unnecessary to specify the precise definition of the time scale. Be sure to show the UTC or offset appropriate to the clock time in use at the time of the event, not the modern time zone, if they differ.

=== <span id="dates" /> Dates and years ===

{{shortcut|WP:YR|MOS:YEAR|WP:DATESNO|MOS:DATEFORMAT}}

These requirements do not apply to dates in quotations or titles. Special rules apply to citations; see {{section link|Wikipedia:Citing sources|Citation style}}.

==== Formats ====

===== <span id="Acceptable date formats" /><span id="years" /><span id="Years" /> Date formats =====

* For issues related to dates in sortable tables, see ''[[Help:Sorting#Date sorting problems|Date sorting problems]]'' or consider using {{nowrap|{{tlx|sort|2008-11-01|1 Nov 2008}}}} or {{nowrap|{{tlx|dts|Nov 1, 2008}}.}}

* Phrases such as {{xt|[[Fourth of July]]}} (or {{xt|July{{nbsp}}Fourth}}, but not {{!xt|July{{nbsp}}4th}}), {{xt|[[Cinco de Mayo]]}}, {{xt|[[Seventh of March Speech]]}} and {{xt|[[Independence Day (Brazil)|Sete de Setembro]]}} are proper names, to which rules for dates do not apply ({{xt|Every Fourth of July celebration includes fireworks}}).

{{anchor|Unacceptable date formats}}{{Shortcut|WP:BADDATEFORMAT|MOS:BADDATEFORMAT}}

{| class="wikitable"

''Note to table:''

{{reflist|group=upper-alpha}}

=====<span id="Format consistency" />Consistency=====

{{shortcut|MOS:DATEUNIFY}}

::{{!xt|Jones, J. (20{{nbsp}}Sep 2008){{nbsp}}... Retrieved Feb{{nbsp}}5, 2009.}}, and

::{{!xt|Jones, J. (20{{nbsp}}Sep 2008){{nbsp}}... Retrieved February{{nbsp}}5, 2009.}}

=====Strong national ties to a topic=====

{{shortcut|WP:STRONGNAT}}

* Articles on topics with strong ties to a particular English-speaking country should generally use the more common date format for that nation. For the United States, this is month before day; for most others, it is day before month. Articles related to Canada may use either format consistently.

* Sometimes the customary format differs from the usual national one: for example, articles on the modern US military use day before month, in accordance with military usage.

=====<span id="Retaining the existing format" />Retaining existing format=====

{{shortcut|WP:DATERET}}

{{See also|Wikipedia:Manual of Style#Retaining the existing variety|l1=Wikipedia:Manual of Style: Retaining the existing variety}}

* If an article has evolved using predominantly one format, the whole article should conform to it, unless there are reasons for changing it based on strong national ties to the topic or consensus on article talk.

* The date format chosen by the first major contributor in the early stages of an article should continue to be used, unless there is reason to change it based on strong national ties to the topic or consensus on article talk.

* Where an article has shown no clear sign of which format is used, the first person to insert a date is equivalent to "the first major contributor".

====<span id="Year numbering systems" /><span id="Eras and other very long periods" />Era style====

{{shortcut|WP:ERA|WP:BCE}}

* '''Other era systems''' may be appropriate in an article. In such cases, dates should be followed by a conversion to Dionysian (or vice versa) and the first instance should be linked: "Qasr-al-Khalifa was built in 221{{nbsp}}[[Hijri year|AH]] (836{{nbsp}}CE)" or "in 836{{nbsp}}AD (221{{nbsp}}[[Hijri year|AH]])".

** [[Astronomical year numbering]] follows the Common Era and does not require conversion, but the first instance of a non-positive year should still be linked: "{{xt|The March equinox passed into Pisces in [[Astronomical year numbering|year −67]].}}"

====Julian and Gregorian calendars====

{{shortcut|WP:OSNS|WP:JG}}

{{see also|Old Style and New Style dates}}

A date can be given in any appropriate calendar, as long it is (at the minimum) given in the [[Julian calendar]] or the [[Gregorian calendar]] or both, as described below. For example, an article on the early [[history of Islam]] may give dates in both [[Islamic calendar|Islamic]] and Julian calendars. Where a calendar other than the Julian or Gregorian is used, the article must make this clear.

* Current events are dated using the Gregorian calendar.

* Dates for Roman history before 45{{nbsp}}BC are given in the [[Roman calendar]], which was neither Julian nor Gregorian. When (rarely) the Julian equivalent is certain, it may be included.

* For dates in early Egyptian and Mesopotamian history, Julian or Gregorian equivalents are often uncertain. Follow the consensus of reliable sources, or indicate their divergence.

The dating method used should follow that used by reliable secondary sources (or if reliable sources disagree, that used most commonly, with an explanatory [[WP:FOOT|footnote]]).

At some places and times, the new year began on a date other than 1{{nbsp}}January. For example, in England and its colonies until 1752, the year began on [[Annunciation Day]], 25{{nbsp}}March; see the [[New Year|New Year article]] for other styles. In writing about historical events, however, years should be assumed to have begun on 1{{nbsp}}January (see the example of the execution of Charles I in "[[Old Style and New Style dates#Differences in the start of the year|Differences in the start of the year]]"); if there is reason to use another start-of-year date, this should be noted.

If there is a need to mention [[Old Style and New Style dates|Old or New Style]] dates in an article (as in the [[Glorious Revolution]]), a footnote should be provided on the first usage, stating whether the ''New Style'' refers to a start of year adjustment or to the Gregorian calendar (it can mean either).

====<span id="Other date ranges" /><span id="Dates of birth and death" />Ranges====

{{shortcut|MOS:DOB|WP:MOSBD|WP:BORN|WP:MOSDOB|WP:OTHERDATE|WP:DATEOTHER|WP:DATERANGE}}

: Or use an en dash: {{xt|raids of 30{{ndash}}31{{nbsp}}May 1942}};{{nbsp}} {{xt|raids of {{nobr|31{{nbsp}}May{{snd}}1{{nbsp}}June}} 1942}}.

* Use a dash, or a word such as ''from'' or ''between'', but not both: {{xt|from 1881 to 1886}} (not {{!xt|{{nobr|from 1881{{ndash}}86}}}});{{nbsp}} {{xt|between June{{nbsp}}1 and July{{nbsp}}3}} (not {{!xt|{{nobr|between June{{nbsp}}1{{snd}}July{{nbsp}}3}}}})

Use [[:Category:Date mathematics templates|date mathematics templates]] for age calculations in infoboxes and so on; see [[Wikipedia:Manual of Style/Biographies]].

====Uncertain, incomplete, or approximate dates====

* To indicate ''around,'' ''approximately'', or ''about'', the use of the spaced, unitalicised form {{xt|c.{{nbsp}}1291}} (or the {{t|circa}} template) is preferred over {{!xt|circa}}, {{!xt|ca}}, {{!xt|ca.}}, {{!xt|approximately}}, or {{!xt|approx.}}:

:{{in5|2}}&bull;{{in5|2}} {{xt|'''Anne Smith''' (born 1912 or 1913; died 2013){{nbsp}}...}}

* Other forms of uncertainty should be expressed in words, either in article text or in a footnote: {{xt|April{{nbsp}}14, 1224 (unattested date)}}. Do not use a question mark ({{!xt|1291?}}) for such purposes, as this fails to communicate the nature of the uncertainty.

===<span id="Day, month and season names" /><span id="Longer periods" />Other periods===

====Days of the week====

*Days of the week are capitalized ({{xt|Sunday}}, {{xt|Wednesday}}).

====Months====

{{shortcut|WP:MONTH|MOS:MONTH}}

:*An exception is the {{nowrap|{{small caps|YYYY-MM-DD}}}} format e.g. {{xt|{{nowrap|2001-03-05}}}} for March 5, 2001 (but note that this format has restricted use{{mdashb}}see {{section link||Date formats}}).

:*Do not use {{nowrap|{{small caps|YYYY-MM}}}} format, because it can be mistaken for a range of years ({{!xt|{{nowrap|2001-03}}}}, if used to denote March 2001, may be misread as referring to the years {{nobr|2001{{ndash}}2003}}).

====Seasons====

{{shortcut|WP:SEASON|MOS:SEASON}}

*Consider instead {{xt|early 1995}};{{nbsp}} {{xt|the first quarter of 1995}};{{nbsp}} {{xt|January to March 1995;}} {{nbsp}} {{xt|spent the southern summer in Antarctica;}}.

*Using seasons is appropriate in instances like these: {{xt|the autumn harvest}};{{nbsp}} {{xt|migration typically begins in mid-spring}}.

====Decades====

{{shortcut|WP:DECADE|MOS:DECADE}}

:*Two digits (with a preceding apostrophe) may be used as an alternative to four digits, ''but only if this is a well-established phrase seen in reliable sources'' ({{xt|the{{nbsp}}Roaring{{nbsp}}'20s}},{{nbsp}} {{xt|the{{nbsp}}Gay{{nbsp}}'90s}},{{nbsp}} {{xt|condemning the '60s counterculture}}, but {{xt|grew up in 1960s Boston, moving to Dallas in{{nbsp}}1971}}, and do not write {{!xt|the{{nbsp}}90's}};{{nbsp}} {{!xt|the{{nbsp}}90s}};{{nbsp}} or {{!xt|the{{nbsp}}90s'}}).

:*A third alternative (where seen in reliable sources) is to spell the decade out, capitalized: {{xt|changing attitudes of the Sixties}}

====<span id="centuries" /><span id="millennia" />Centuries and millennia====

{{shortcut|WP:CENTURY|WP:MILLENNIUM}}

* Centuries and millennia are identified using either figures ({{xt|the 18th{{nbsp}}century}}, not {{!xt|XVIII century}}) or words ({{xt|the second millennium}}).<!--actually, I wonder whether "1st millennium" and "2nd millennium" are really appropriate -- they look funny--> When used adjectivally they contain a hyphen ({{xt|nineteenth-century painting}} or {{xt|19th-century painting}}). Do not capitalize ({{!xt|the best Nineteenth-century paintings}};{{nbsp}} {{!xt|during the Nineteenth Century}}).

:*See [[WP:ENDASH]] for use of hyphens and dashes in obscure situations.

====Abbreviations for long periods of time====

*When the term is frequent, combine the abbreviations "yr" for "years" and "ya" for "years ago" with prefixes "k" for "thousand" (kya, kyr), "m" for "million" ([[mya (unit)|mya]], myr), and "b" for "billion" ([[bya]], byr).

*In academic contexts, [[annum]]-based units are often used: "ka" (kiloannum), "Ma" (megaannum) and "Ga" (gigaannum). Some authorities, such as the [[British Museum]], simply spell out "years ago".

*For any of these abbreviations, show the meaning parenthetically on first occurrence and again where use is extensive,{{huh}} or might be a standalone topic of interest. For source quotations use square brackets, as in {{xt|"a measured Libby radiocarbon date of 35.1{{nbsp}}mya [million years ago] required calibration ..."}}

==Numbers==

===Numbers as figures or words===

{{shortcut|WP:NUMERAL|MOS:NUMERAL|WP:SPELL09|MOS:SPELL09}}

''See also information on specific situations, elsewhere in this guideline.''

Generally, in article text:

* Integers from zero to nine are spelled out in words

:* SI prefixes and symbols, such as ''giga-'' ''(G)'' and ''tera-'' (''T''), should be restricted to use in scientific and engineering expressions.

:*Sometimes, the [[Wikipedia:Manual of Style#National varieties of English|variety of English]] used in an article may call for the use of a numbering system other than the Western thousands-based system. For example, the [[South Asian numbering system]] is convention{{shy}}ally used in [[South Asian English]]. In those situations, link the first spelled-out instance of each quantity (e.g. <code><nowiki>[[crore]]</nowiki></code>, which yields [[crore]]). (If no instances are spelled out, provide a note after the first instance directing the reader to the article about the numbering system.) Also, provide a conversion to Western numbers for the first instance of each quantity, and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write {{xt|three [[crore]] (thirty million)}}. Group digits in Western thousands-based style (e.g., {{xt|30,000,000}}; not {{!xt|3,00,00,000}}): see {{section link||Delimiting (grouping of digits)}} below. (Note that the variety of English does not uniquely determine the method of numbering in an article. Other considerations, such as conventions used in mathematics, science and engineering, may also apply, and the choice and order of formats and conversions is a matter of editorial discretion and consensus.)

{{anchor|Numeral notes}}{{shortcut|WP:NUMNOTES}}

Notes and exceptions:

* Proper names, technical terms, and the like are never altered:

{{xt|''The Sixth Sense''}};{{nbsp}} {{xt|5{{nbsp}}Channel Street}};{{nbsp}} {{xt|Channel{{nbsp}}5}};{{nbsp}} {{xt|Chanel No. 5}};{{nbsp}} {{xt|Fourth Estate}};{{nbsp}} {{xt|Third Reich}};{{nbsp}} {{xt|Second Judicial District}};{{nbsp}} {{xt|First Amendment}};{{nbsp}} {{xt|''Zero Hour''}};{{nbsp}}<!--blast off!-->

* Avoid beginning a sentence with figures:

:{{in5|2}}&bull;{{in5|2}} Not {{!xt|There were many attacks. 23 men were killed}}, but {{xt|There were many attacks; 23{{nbsp}}men were killed}} or {{xt|There were many attacks. Twenty-three men were killed}}.

:{{in5|2}}&bull;{{in5|2}} Not {{nowrap|{{!xt|1945 and 1950 saw crucial elections}}}} (nor {{nowrap|{{!xt|Nineteen forty-five and 1950 saw crucial elections}}}}{{snd}} because comparable numbers should be both written in words or both in figures) but {{nowrap|{{xt|The elections of 1945 and 1950 were crucial.}}}}<!--Examples still need work, and need something about "nineteen forty-five"-type years-->

:*Exception: Where a proper name, technical term, etc., itself beginning with a numeral, opens the sentence ({{xt|1-Naphthylamine is typically synthesized via the Felden{{shy}}shlager{{ndash}}Glocken{{shy}}spiel process}}) although this can usually be avoided by rewording ({{xt|Felden{{shy}}shlager{{ndash}}Glocken{{shy}}spiel is the process typically used in the synthesis of 1-Naphthylamine}}).

{{shortcut|MOS:ORDINAL|WP:ORDINAL}}<!--positioned before (rather than after) section in question to avoid crash of shortcut boxes when sections are short-->

===Ordinals===

* {{anchor|1st}}[[Ordinal numbers (linguistics)|Ordinal]] suffixes (''st'', ''nd'', ''rd'', ''th'') are not [[superscript]]ed ({{xt|123rd}} and {{xt|496th}}, not {{!xt|123^rd}} nor {{!xt|496^th}}).

* Do not use a dot ({{!xt|.}}) or the ordinal mark ({{!xt|&#186;}}) to indicate ordinals.

===Fractions===

{{shortcut|MOS:FRAC}}

* Nouns following [[Fraction (mathematics)#Simple, common, or vulgar fractions|simple fractions]] are singular ({{xt|He took {{frac|4}} dose}},{{nbsp}} {{xt|net change in score was &minus;{{frac|2}} point}},{{nbsp}} {{xt|{{frac|3|2}} dose}}).

* Nouns following mixed numbers are plural ({{xt|victim knew even 1{{frac|1|2}} doses could be fatal}},{{nbsp}} {{xt|they sailed for 4{{frac|2}} nautical miles}}).

===<span id="Decimal points" />Decimals===

{{shortcut|WP:DECIMAL|MOS:DECIMAL}}

* Nouns following a number expressed as a decimal are plural ({{xt|averaging 0.7 years}}).

* Indicate repeating digits with an [[Vinculum (symbol)|overbar]] e.g. {{nowrap|<code><nowiki>14.31{{overline|28}}</nowiki></code>}} gives {{xt|14.31{{overline|28}}}}. (Consider explaining this notation on first use.) Do not write e.g. {{nobr|{{!xt|14.31(28)}}}} because it resembles notations for {{section link||Uncertainty}}.

====<span id="Delimiting (grouping of digits)" />Grouping of digits====

* Left of the decimal point: Five or more digits should be grouped (and exactly four digits may ''optionally'' be grouped) into triples separated by commas (''never'' period/full stop): {{xt|12,200}};{{nbsp}}{{nbsp}} {{xt|255,200}};{{nbsp}}{{nbsp}} {{xt|8,274,527}};{{nbsp}}{{nbsp}} {{xt|1,250}} (optionally {{xt|1250}}).

* Right of the decimal point: Five or more digits may be grouped into triples separated by spaces: {{xt|{{val|99.123456}}}}.

:* In mathematics-oriented articles, digits right of the point may be grouped into fives: {{xt|{{gaps|3.14159|26535|89793|23846|...}}}}.

Delimiting style should be consistent throughout a given article.

''Markup:'' Templates {{t|val}}, {{t|val/delimitnum}} and {{t|gaps}} may be useful in grouping digits. Use of hard-coded spaces, such as the regular space character, the non-breaking space (<code>&amp;nbsp;</code>), and the thin space (<code>&amp;thinsp;</code> or {{t|thinsp}}), is problematic for [[screen reader]]s because they read out each group of digits as separate numbers (e.g. {{xt|30 000}} is read as "thirty zero zero zero").<!--perhaps should say something more re nbsp here since some will hand-code the markup; also, do {{val}} and [[gaps}} use nbsp? should they? (answer may be different left of the point vs right of the point)-->

===Percentages===

{{shortcut|MOS:PERCENT|WP:PERCENT|WP:%}}

* In the body of scientific/{{zwsp}}technical articles, and in '''tables and infoboxes''' of any article, the symbol ''%'' (unspaced) is more common: {{xt|71%}}, not {{!xt|71 %}} or {{!xt|three %}}. Ranges: {{xt|10{{ndash}}12%}}, not {{!xt|10%{{ndash}}12%}} or {{!xt|10 to 12%}}.

* When expressing the difference between two percentages, do not confuse a percentage change with a change in [[percentage point]]s.

===<span id="Scientific notation, engineering notation, and uncertainty" />Scientific and engineering notation===

* [[Scientific notation]] always has a single nonzero digit to the left of the point: not {{!xt|{{val|60.22|e=22}}}}, but {{xt|{{val|6.022|e=23}}}}.

* In a table column (or other presentation) in which all values can be expressed with a single power of 10, consider giving e.g. {{xt|&times;&nbsp;10{{sup|7}}}} once in the column header, and omitting it in the individual entries. (''Markup:''<code><nowiki>&amp;times;&amp;nbsp;10{{sup|7}}</nowiki></code>)

* In both notations, the number of digits indicates the precision. For example, {{xt|{{val|5|e=3}}}} means rounded to the nearest thousand; {{xt|{{val|5.0|e=3}}}} to the nearest hundred; {{xt|{{val|5.00|e=3}}}} to the nearest ten; and {{xt|{{val|5.000|e=3}}}} to the nearest unit.

''Markup:'' {{t|Val}} and {{t|e}} may be used to format exponential notation.

===Uncertainty and rounding <span id="Uncertainty" /> <span id="Large numbers" />===

{{shortcut|MOS:UNCERTAINTY|MOS:LARGENUM}}

:{{in5|2}}&bull;{{in5|2}} {{xt|A local newspaper poll predicted 52% of the vote would go to Smith, but did not publish information on the uncertainty of this estimate.}}

*The {{tl|undue precision}} template may be added to figures appearing to be overprecise.

* Avoid using "approximately", "about'' and similar terms with figures that have merely been approximated or rounded in a normal and expected way, unless the reader might otherwise be misled.

:{{in5|2}}&bull;{{in5|2}} {{xt|The tallest player was 6 feet 3 inches}} ({{nobr|not {{!xt|... about 6 feet 3 inches}}}}{{mdashb}}heights are conventionally reported only to the nearest inch, even though greater precision may be available in principle).<!-- please, no lectures about SI -- if you can give a parallel metric example please do so-->

::''but'' {{xt|The man police are seeking is about 5 feet 8 inches tall, with dark hair}}.

* The reader may be assumed to interpret large round numbers ({{xt|100,000 troops}}) as approximations. Writing a quantity in words ({{xt|one hundred thousand troops}}) can further emphasize its approximate nature.

*See {{section link||Unit conversions}} below for precision issues when converting units.

===Non-[[radix|base]]-10 notations===

{{shortcut|MOS:BASE|MOS:RADIX|MOS:BINARY|MOS:HEX}}

* In all other articles, use <code>&lt;sub></code> to create subscripts: {{xt|137₉}}, {{xt|241₃}}. ''Markup:'' {{xt|137<code><nowiki>₉</nowiki></code>}}, {{xt|241<code><nowiki>₃</nowiki></code>}}

* For bases above 10, use symbols conventional for that base (as seen in reliable sources) e.g. for [[base 16]] use {{nobr|0{{ndash}}9A{{ndash}}F}}.

== Units of measurement ==

{{Shortcut|WP:UNIT|WP:UNITS|WP:METRIC|WP:MEASUREMENT}}

===Choice of units===

Quantities are typically expressed using an appropriate "main" unit, in some cases followed by a conversion to other units in parentheses. For use of such conversions, see {{section link||Unit conversions}} below.

*In '''most articles, including all scientific articles''', the main units chosen will be [[International System of Units|SI]] units, [[Non-SI units mentioned in the SI|non-SI units officially accepted for use with the SI]], or such other units as are conventional in reliable-source discussions of the article topic (such as [[revolutions per minute]] (rpm) for angular speed, [[hand (unit)|hand]]s for heights of horses, etc.) Example: {{xt|44{{nbsp}}kilograms (97{{nbsp}}lb)}}. The following exceptions apply:

*In '''non-scientific articles relating to the United States''', the main units are [[United States customary units|US customary]], e.g. {{xt|97{{nbsp}}pounds (44{{nbsp}}kg)}}.

** imperial pints are used for quantities of draught beer/{{zwsp}}cider and bottled milk;

** UK engineering-related articles, including all bridges and tunnels, generally use the system of units that the topic was drawn-up in (but road distances are given in imperial units, with a metric conversion).

''Special considerations:''

* Quantities set via definition (as opposed to measured quantities) should be given first in the units used in the definition, even if this makes the structure of presentation inconsistent: {{xt|During metrification, the speed limit was changed from 30{{nbsp}}miles per hour (48{{nbsp}}kilometers/hour) to 50{{nbsp}}km/h (31{{nbsp}}mph)}}.

* Nominal quantities (e.g. {{nowrap|"[[2x4|2 &times; 4]]"}} lumber) require consideration of whether the article is concerned with the item's actual dimensions or merely with its function. In some cases only the nominal quantity may suffice; in others it may be necessary to give the nominal size (often in non-SI units), the actual size in non-SI units, and the actual size in SI units.

* Where the primary units in the article are different from the primary units in the source, ensure that the precision of the converted quantity in the article is comparable to the precision of the quantity from the source (see {{section link||Unit conversions}} below). The {{tl|convert}} template has a <code>|disp=flip</code> flag, which tells it to treat the converted unit as primary and the original unit as secondary, for use in such situations.

===Unit names and symbols===

:''Definitions:''

:*Examples of '''unit names''': foot, meter, kilometer.

:*Examples of '''unit symbols''': ft, m, km.

* Unit names and symbols should follow the practice of reliable sources.

* In prose, unit names should be given in full if used only a few times, but symbols may be used when a unit (especially one with a long name) is used repeatedly, after spelling out the first use (e.g. {{xt|Up to 15{{nbsp}}kilograms of filler is used for a batch of 250{{nbsp}}kg}}).

:* With ''by'' the unit need be given only once: {{nobr| {{xt|1 by 3 by 6 metres}} }} or {{nobr| {{xt|1 by 3 by 6 m}} }}

:* The unspaced letter {{xt|x}} may be used in common terms such as {{xt|[[4x4]]}}.

{| class="wikitable"

|+ Unit names and symbols—General guidelines

''Note to table:''

{{reflist | group=upper-alpha|close=1}}

===Specific units===

* The following table lists only units that need special attention.

* The [http://www.bipm.org/en/si/ SI standard] should be consulted for guidance on use of other SI units. [http://www.bipm.org/en/si/si_brochure/chapter4/4-1.html "Tables 6, 7, 8, and 9"] give additional guidance on non-SI units.

{|class="wikitable"

|+ Guidelines on specific units

| {{ xt|Cal}}

|}

====Quantities of bytes and bits <span id="Binary prefixes" />====

{{shortcut|WP:COMPUNITS}}

{{Bit and byte prefixes}}

Follow these recommendations when using these prefixes in Wikipedia articles:

* Following the SI standard, a lower-case {{xt|k}} should be used for "kilo-" whenever it means 1000 in computing contexts, whereas a capital {{xt|K}} should be used instead to indicate the binary prefix for 1024 according to JEDEC. (If, under the exceptions detailed further below, the article otherwise uses IEC prefixes for binary units, use {{xt|Ki}} instead).

* Do not assume that the binary or decimal meaning of prefixes will be obvious to everyone. Explicitly specify the meaning of k and K as well as the primary meaning of M, G, T, etc. in an article ({{tl|BDprefix}} is a convenient helper). Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.

* Avoid inconsistent combinations such as {{!xt|A 64{{nbsp}}MB (67,108,864-byte) video card and a 100{{nbsp}}GB {{nowrap|(100 &times; 1000³-byte)}} hard drive}}. Footnotes, such as those seen in [//en.wikipedia.org/w/index.php?title=Power_Macintosh_5500&oldid=218088888 {{nowrap|Power Macintosh 5500}}], may be used for disambiguation.

* Unless explicitly stated otherwise, one byte is eight bits (see [[Byte#History|History of ''byte'']]).

The [[IEC prefix]]es ''kibi-'', ''mebi-'', ''gibi-'', etc. (symbols Ki, Mi, Gi, etc.) are rarely used, even in technical articles, so are generally not to be used except:<ref>Wikipedia follows common practice regarding [[byte]]s and other data traditionally quantified using [[binary prefix]]es (e.g. mega- and kilo-, meaning 2²⁰ and 2¹⁰ respectively) and their unit symbols (e.g. MB and KB) for RAM and [[decimal prefix]]es for most other uses. Despite the IEC's 1998 International Standard creating several new binary prefixes (e.g. mebi-, kibi-) to distinguish the meaning of the decimal [[SI prefix]]es (e.g. mega- and kilo-, meaning 10⁶ and 10³ respectively) from the binary ones, and the subsequent incorporation of these IEC prefixes into the [[IEC 80000-13|International System of Quantities]] (ISQ), consensus on Wikipedia in computing-related contexts currently favours the retention of the more familiar but ambiguous units "KB", "MB", "GB", "TB", "PB", "EB", etc. over use of unambiguous IEC binary prefixes. For detailed discussion, see [[Wikipedia talk:Manual of Style (dates and numbers)/Archive/Complete rewrite of Units of Measurements (June 2008)|Complete rewrite of Units of Measurements (June 2008)]].</ref>

* when the majority of cited sources on the article topic use IEC prefixes,

* when explicitly discussing the IEC prefixes,

* in articles in which both types of prefix are used with neither clearly primary, or in which converting all quantities to one or the other type would be misleading or lose necessary precision, or declaring the actual meaning of a unit on each use would be impractical.

===Unit conversions===

{{shortcut|MOS:CONVERSIONS|WP:MOSCONVERSIONS}}

* In a '''direct quotation''', always retain the source units. Any conversions can be supplied either in the quote itself (in square brackets, following the original measurement) or in a footnote. See [[Wikipedia:Footnotes|footnoting]] and [[Wikipedia:Citing sources|citing sources]].

* {{t|Units attention}} may be added to articles needing general attention regarding choice of units and unit conversions.

==<span id="Currencies" /> Currencies and monetary values==

{{shortcut|WP:$|WP:&pound;|WP:€|MOS:CURRENCY}}

* In '''country-specific articles''', such as [[Economy of Australia]], use the currency of the subject country.

* In '''non-country-specific articles''' such as [[Wealth]], use US dollars ({{xt|$123}}), euros ({{xt|&euro;123}}), or pounds sterling ({{xt|&pound;123}}).

===Currency names===

* Do not capitalize the names of currencies, currency subdivisions, coins and banknotes except e.g. at the start of a sentence.<!--It's a bit more complicated than this -- clearly "Australain dollar" uses a capital on Austrailian"-->

* The [[pound sterling]] is represented by the {{xt|&pound;}} symbol, with one horizontal bar. The double-barred {{!xt|&#8356;}} symbol is ambiguous, as it has also been used for the [[Italian lira]] and other currencies. For non-British currencies that use pounds or a pound symbol (e.g. the [[Irish pound]], IR&pound;) use the symbol convention{{shy}}ally preferred for that currency.<!--If no modern currency still uses the ₤ symbol, the developers should be asked to remove it from the edit tool box to prevent its misuse.-->

* If there is no common English abbreviation or symbol, follow the [[ISO 4217]] standard. See also [[List of circulating currencies]].

===Format===

* A period (full stop) is used as the decimal point{{mdashb}}never a comma ({{xt|$6.57}}, not {{!xt|$6,57}}).

* In general, a currency symbol should be accompanied by a numeric amount e.g. not {{!xt|He converted his US$ to A$}} but {{xt|He converted his US dollars to Australian dollars}} or {{xt|He exchanged the US$100 note for Australian dollars}}.

:*Exceptions may occur in tables and infoboxes where space is limited e.g. {{xt|''Currencies accepted for deposit:'' [[United States dollar|US$]], [[Swiss franc|SFr]], [[British pound|GB&pound;]], [[Euro|&euro;]]}}. It may be appropriate to wikilink such uses, or add an explanatory note.

===Conversions===

* Conversions of '''less-familiar currencies''' may be provided in terms of more familiar currencies{{mdashb}}such as the US dollar, euro or pound sterling{{mdashb}}using an appropriate rate (which is often ''not'' the current exchange rate). Conversions should be in parentheses after the original currency, rounding to avoid [[false precision]] (two significant digits is usually sufficient, as most exchange rates fluctuate significantly), with at least the year given as a rough point of conversion rate reference; e.g. {{xt|Since 2001 the grant has been 10,000,000 [[Swedish krona|Swedish kronor]] ($1.4M, &euro;1.0M, or &pound;800k {{as of|2009|08|lc=on}})}}, not {{!xt|($1,390,570, &euro;971,673 or &pound;848,646)}}.<!-- is "800k" really acceptable?-->

* For '''obsolete currencies''', provide an equivalent (formatted as a conversion) if possible, in the modern replacement currency (e.g. decimal pounds for historical pre-decimal pounds-and-shillings), or a US-dollar equivalent where there is no modern equivalent.

* In some cases it may be appropriate to provide a conversion accounting for inflation or deflation over time. See {{t|Inflation}} and {{t|Inflation-fn}}.

==<span id="Minus sign" />Common mathematical symbols==

{{shortcut|WP:COMMONMATH||MOS:MINUS}}

| <code><nowiki>''x'' &amp;ge; ''y''</nowiki></code>

|}

==Geographical coordinates==

<div style="float:right; width:100px;">{{Shortcut|WP:Coordinates|MOS:COORDS}}</div>

:'''For draft guidance on, and examples of, coordinates for linear features, see [[Wikipedia:WikiProject Geographical coordinates/Linear]]'''.

:'''Quick guide''':

{{coord how-to}}

[[Geographical coordinates]] on Earth should be entered using a template to standardise the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically.

First, [[Wikipedia:Obtaining geographic coordinates|obtain the coordinates]]. Avoid [[Wikipedia:WikiProject Geographical coordinates#Precision|excessive precision]].

Two types of template are available:

* {{tl|coord}} offers users a choice of display format through [[Help:User style|user style]]s, emits a [[Geo microformat]], and is recognised (in the ''title'' position) by the "nearby" feature of Wikipedia's mobile apps and by external partners such as Google (-Maps and -Earth) and Yahoo.

* Infoboxes such as {{tl|Infobox settlement}}, which automatically emit {{Tl|Coord}}.

The following formats are available.

* For degrees only (including decimal values): {{tlc|coord|2={{var|dd}}|3={{var|N/S}}|4={{var|dd}}|5={{var|E/W}}}}

* For degrees/minutes: {{tlc|coord|2={{var|dd}}|3={{var|mm}}|4={{var|N/S}}|5={{var|dd}}|6={{var|mm}}|7={{var|E/W}}}}

* For degrees/minutes/seconds: {{tlc|coord|2={{var|dd}}|3={{var|mm}}|4={{var|ss}}|5={{var|N/S}}|6={{var|dd}}|7={{var|mm}}|8={{var|ss}}|9={{var|E/W}}}}

where:

* {{var|dd}}, {{var|mm}}, {{var|ss}} are the degrees, minutes and seconds, respectively;

* {{var|E/W}} is either ''E'' for eastern or ''W'' for western [[longitude]]s;

* negative values may be used in lieu of ''S'' and ''W'' to denote southern and western [[hemisphere]]s

For example:

The city of [[Oslo]], located at '''59° 55&prime; N, 10° 44&prime; E''', enter:

:<code><nowiki>{{coord|59|55|N|10|44|E}}</nowiki></code>{{mdashb}}which becomes {{coord|59|55|N|10|44|E}}

For a country, like [[Botswana]], less precision is appropriate:

:<code><nowiki>{{coord|22|S|24|E}}</nowiki></code>{{mdashb}}which becomes {{coord|22|S|24|E}}

Higher levels of precision are obtained by using seconds:

:<code><nowiki>{{coord|33|56|24|N|118|24|00|W}}</nowiki></code>{{mdashb}}which becomes {{coord|33|56|24|N|118|24|00|W}}

Coordinates can be entered as decimal values

:<code><nowiki>{{coord|33.94|S|118.40|W}}</nowiki></code>{{mdashb}}which becomes {{coord|33.94|S|118.40|W}}

Increasing or decreasing the number of decimal places controls the precision. Trailing zeros should be used as needed to ensure that both values have the same level of precision.

[[London Heathrow Airport]], [[Amsterdam]], [[Jan Mayen]] and [[Mount Baker]] are examples of articles that contain geographical coordinates.

Generally, the larger the object being mapped, the ''less precise'' the coordinates should be. For example, if just giving the location of a city, precision greater than 100{{nbsp}}meters is not needed unless specifying a particular point in the city, for example the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10{{nbsp}}meters or even one meter in some cases (1′′ ~15{{nbsp}}m to 30{{nbsp}}m, 0.0001° ~5.6{{nbsp}}m to 10{{nbsp}}m).

The final field, following the E/W, is available for attributes such as ''type'', ''region'' and ''scale''.

When adding coordinates, please remove the {{tl|coord missing}} tag from the article, if present.

For more information, see [[Wikipedia:WikiProject Geographical coordinates|the geographical coordinates WikiProject]].

Templates other than {{tl|coord}} should use the following variable names for coordinates: {{var|lat_d}}, {{var|lat_m}}, {{var|lat_s}}, {{var|lat_NS}}, {{var|long_d}}, {{var|long_m}}, {{var|long_s}}, {{var|long_EW}}.

==See also==

* [[Wikipedia:Naming conventions (numbers and dates)]]

* {{section link|m:Help:Calculation|Displaying numbers and numeric expressions}} at Meta

{{Math templates}}

==Notes and references==

{{Reflist|35em}}

{{Style wide}}

[[Category:General style guidelines]]

[[Category:Wikipedia Manual of Style (formatting)]]