Editing Roman numerals (section)

==Modern use==
By the 11th century, Arabic numerals had been introduced into Europe from [[al-Andalus]], by way of [[Arab]] traders and arithmetic treatises. Roman numerals, however, proved very persistent, remaining in common use in the West well into the 14th and 15th centuries, even in accounting and other business records (where the actual calculations would have been made using an [[abacus]]). Replacement by their more convenient "Arabic" equivalents was quite gradual, and Roman numerals are still used today in certain contexts. A few examples of their current use are:

[[File:Carlos IV Coin.jpg|thumb|upright=1.1|Spanish [[Spanish real|Real]] using {{rn|IIII}} instead of {{rn|IV}} as regnal number of [[Charles IV of Spain|Charles {{Rn|IV}} of Spain]].|alt=]]
* Names of monarchs and popes, e.g. [[Elizabeth II]] of the United Kingdom, [[Pope Leo XIV]]. These are referred to as [[regnal number]]s and are usually read as [[Ordinal numbers (linguistics)|ordinals]]; e.g. {{rn|II}} is pronounced "the second". This tradition began in Europe sporadically in the [[Middle Ages]], gaining widespread use in England during the reign of [[Henry VIII]]. Previously, the monarch was not known by numeral but by an [[epithet]] such as [[Edward the Confessor]]. Some monarchs (e.g. [[Charles IV of Spain]], [[Louis XIV of France]] and [[William IV of the United Kingdom|William IV of Great Britain]]) seem to have preferred the use of {{rn|IIII}} instead of {{rn|IV}} on their coinage (see illustration).
* [[Suffix (name)#Generational titles|Generational suffixes]], particularly in the U.S., for people sharing the same name across generations, such as [[William Howard Taft IV]]. These are also usually read as ordinals.
* In the [[French Republican Calendar#Converting from the Gregorian Calendar|French Republican Calendar]], initiated during the [[French Revolution]], years were numbered by Roman numerals – from the year {{rn|I}} (1792) when this calendar was introduced to the year {{rn|XIV}} (1805) when it was abandoned.
* [[File:Cambridge Main Public Library 1888.jpg|thumb|upright=1.1|The year of construction of the [[Cambridge Public Library]] (Massachusetts, U.S.), 1888, displayed in "standard" Roman numerals on its facade.]]<!--
--> The year of production of films, television shows and other works of art within the work itself. Outside reference to the work will use regular Arabic numerals.
* Hour marks on [[timepiece]]s. In this context, 4 is often written {{rn|IIII}}.
* The year of construction on building [[façade]]s and [[cornerstone]]s.
* Page numbering of prefaces and introductions of books, and sometimes of appendices and annexes, too.
* Book volume and chapter numbers, as well as the several acts within a play (e.g. Act {{Rn|iii}}, Scene 2).
* [[Sequel]]s to some films, video games, and other works (as in ''[[Rocky II]]'', ''[[Grand Theft Auto V]]'', ''[[Myst III: Exile]]'').
* [[Outline (summary)|Outlines]] that use numbers to show hierarchical relationships.
* Occurrences of a recurring grand event, for instance:
** The [[Summer Olympic Games|Summer]] and [[Winter Olympic Games]] (e.g. the [[2010 Winter Olympics|XXI Olympic Winter Games]]; the [[2012 Summer Olympics|Games of the XXX Olympiad]]).
** The [[Super Bowl]], the annual championship game of the [[National Football League]] (e.g. [[Super Bowl XLII]]; [[Super Bowl 50]] was a one-time exception<ref>{{Cite web |last=Rosenthal |first=Gregg |date=June 4, 2014 |title=NFL won't use Roman numerals for Super Bowl 50 |url=https://www.nfl.com/news/nfl-won-t-use-roman-numerals-for-super-bowl-50-0ap2000000355943 |url-status=live |archive-url=https://web.archive.org/web/20151201194151/http://www.nfl.com/news/story/0ap2000000355943/article/nfl-wont-use-roman-numerals-for-super-bowl-50 |archive-date=1 December 2015 |access-date=5 November 2014 |publisher=National Football League}}</ref>).
** [[WrestleMania]], the annual [[professional wrestling]] event for [[WWE]] (e.g. [[WrestleMania XXX]]). This usage has also been inconsistent.

===Specific disciplines===
In [[astronautics]], [[List of orbital launch systems#United States|United States rocket]] model variants are sometimes designated by Roman numerals, e.g. [[Titan I]], [[Titan II]], [[Titan III]], [[Saturn I]], [[Saturn V]].

In [[astronomy]], the [[natural satellite]]s or "moons" of the [[planet]]s are [[Naming of moons#Roman numeral designations|designated]] by capital Roman numerals appended to the planet's name. For example, [[Titan (moon)|Titan]]'s designation is [[Saturn]] {{rn|VI}}.<ref name="jplsats-disc">{{Cite web |date=15 November 2021 |title=Planetary Satellite Discovery Circumstances |url=https://ssd.jpl.nasa.gov/sats/discovery.html |access-date=7 January 2022 |website=JPL Solar System Dynamics |publisher=NASA}}</ref>

In [[chemistry]], Roman numerals are sometimes used to denote the [[group (periodic table)|groups]] of the [[periodic table]], but this has officially been deprecated in favour of Arabic numerals.<ref name="Fluck 1988">{{Cite journal |last=Fluck |first=E. |date=1988 |title=New Notations in the Periodic Table |url=http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf |journal=[[Pure and Applied Chemistry|Pure Appl. Chem.]] |publisher=[[International Union of Pure and Applied Chemistry|IUPAC]] |volume=60 |issue=3 |pages=431–436 |doi=10.1351/pac198860030431 |s2cid=96704008 |access-date=24 March 2012}}</ref> They are also used in the [[IUPAC nomenclature of inorganic chemistry]], for the [[oxidation number]] of [[cation]]s which can take on several different positive charges. They are also used for naming [[Phase (matter)|phases]] of [[Polymorphism (materials science)|polymorphic]] [[crystal]]s, such as [[ice]].

In [[education]], school grades (in the sense of year-groups rather than test scores) are sometimes referred to by a Roman numeral; for example, "grade {{rn|IX}}" is sometimes seen for "grade 9".

[[File:9th Aero Squadron AEF.jpg|thumb|upright=1.1|Stylised "{{rn|IX}}" represents "9" in unit emblem of [[9th Aero Squadron]] AEF, 1918.]]

In [[entomology]], the broods of the thirteen- and seventeen-year [[periodical cicadas]] are identified by Roman numerals.

In [[graphic design]], stylised Roman numerals may represent numeric values.

In [[law]], Roman numerals are commonly used to help organize legal codes as part of an [[outline (list)#Alphanumeric outline|alphanumeric outline]]. 
* In numbering [[Act of Parliament (United Kingdom)|UK Acts of Parliament]] within a given year (a given [[parliamentary session|session]] until 1963), [[Local and personal acts of Parliament (United Kingdom)#Local acts|local act]]s have lowercase Roman numerals, whereas [[Act of Parliament (United Kingdom)#Public general acts|public act]]s have plain Arabic numerals and [[Local and personal acts of Parliament (United Kingdom)#Personal acts|personal act]]s have [[Italic type|italic]] Arabic numerals.<ref>{{cite web |title=Introduction to Private and Personal Acts |url=https://www.legislation.gov.uk/changes/chron-tables/private/intro#6ListingNumberingandAnnotationsofActs |website=[[legislation.gov.uk]] |access-date=22 July 2024 |page=6. Listing, Numbering and Annotations of Acts}}</ref>

In [[mathematics]] (including [[trigonometry]], [[statistics]], and [[calculus]]), when a graph includes negative numbers, its quadrants are named using {{rn|I}}, {{rn|II}}, {{rn|III}}, and {{rn|IV}}.<ref>{{Cite web |date=2020-08-04 |title=2.1: Definition and Label Quadrants |url=https://math.libretexts.org/Bookshelves/Applied_Mathematics/Calculus_for_Business_and_Social_Sciences_Corequisite_Workbook_(Dominguez_Martinez_and_Saykali)/02:_Cartesian_Coordinate_System/2.01:_Definition__and_Label_Quadrants |access-date=2025-01-31 |website=Mathematics LibreTexts |language=en}}</ref> These quadrant names signify positive numbers on both axes, negative numbers on the x-axis, negative numbers on both axes, and negative numbers on the y-axis, respectively. The use of Roman numerals to designate quadrants avoids confusion, since Arabic numerals are used for the actual data represented in the graph.

In [[military]] unit designation, Roman numerals are often used to distinguish between units at different levels. This reduces possible confusion, especially when viewing operational or strategic level maps. In particular, army corps are often numbered using Roman numerals (for example, the American XVIII Airborne Corps or the Nazi III Panzerkorps) with Arabic numerals being used for divisions and armies.

In [[music]], Roman numerals are used in several contexts:
* [[movement (music)|Movements]] are often numbered using Roman numerals.
* In [[Roman numeral analysis]], [[Function (music)|harmonic function]] is identified using Roman numerals.
* Individual strings of [[stringed instruments]], such as the [[violin]], are often denoted by Roman numerals, with higher numbers denoting lower strings.

In [[pharmacy]], Roman numerals were used with the now largely obsolete [[apothecaries' system]] of measurement: including {{rn|SS}} to denote "one half" and {{rn|N}} to denote "zero".<ref name="Bachenheimer" /><ref>{{Cite book |last1=Reddy |first1=Indra K. |url=https://books.google.com/books?id=U3QY7gz0C2cC |title=Essential Math and Calculations for Pharmacy Technicians |last2=Khan |first2=Mansoor A. |date=2003 |publisher=CRC Press |isbn=978-0-203-49534-6}}</ref>

In [[photography]], Roman numerals (with zero) are used to denote varying levels of brightness when using the [[Zone System]].

In [[seismology]], Roman numerals are used to designate degrees of the [[Mercalli intensity scale]] of earthquakes.

[[File:Eire Frankng I-IV-1986.jpg|thumb|Example of postage stamp from Ireland (Éire) franked using Roman numeral for the month]]

In [[team sport|sport]] the team containing the "top" players and representing a nation or province, a [[Sports club|club]] or a school at the highest level in (say) [[rugby union]] is often called the "1st {{rn|XV}}", while a lower-ranking [[cricket]] or [[American football]] team might be the "3rd {{rn|XI}}".

In [[tarot]], Roman numerals (with zero) are often used to denote the cards of the [[Major Arcana]].

In [[Republic_of_Ireland|Ireland]], Roman numerals were used until the late 1980s to indicate the month on postage [[Franking]]. In documents, Roman numerals are sometimes still used to indicate the month to avoid confusion over day/month/year or month/day/year formats.

In [[theology]] and [[biblical scholarship]], the [[Septuagint]] is often referred to as {{rn|LXX}}, as this translation of the [[Old Testament]] into Greek is named for the legendary number of its translators (''septuaginta'' being Latin for "seventy").

===Modern use in European languages other than English===
Some uses that are rare or never seen in English-speaking countries may be relatively common in parts of [[continental Europe]] and in other regions (e.g. [[Latin America]]) that use a European language other than English. For instance:

Capital or [[Small caps|small capital]] Roman numerals are widely used in [[Romance languages]] to denote {{strong|centuries}}, e.g. the French ''{{lang|fr|{{Smallcaps|xviii}}<sup>e</sup> siècle}}''<ref>{{Cite book |title=Lexique des règles typographiques en usage à l'imprimerie nationale |date=March 2011 |publisher=[[Imprimerie nationale]] |isbn=978-2-7433-0482-9 |edition=6th |location=Paris |pages=126 |language=fr}} ''On composera en chiffres romains petites capitales les nombres concernant : ↲ 1. Les siècles.''</ref> and the Spanish ''{{lang|es|siglo {{Smallcaps|xviii}}}}'' (not ''{{lang|es|{{Smallcaps|xviii}} siglo}}'') for "18th century". Some Slavic and Turkic languages (especially in and adjacent to Russia) similarly favour Roman numerals (e.g. Russian {{lang|ru|XVIII век}}, Azeri {{lang|az|XVIII əsr}} or Polish {{lang|pl|wiek XVIII}}<ref>{{Cite web |title=cyfry arabskie a zapis wieku |url=https://poradnia-jezykowa.uni.lodz.pl/faq/cyfry-arabskie-a-zapis-wieku/ |first=Katarzyna |last=Burska |website=Poradnia językowa Uniwersytetu Łódzkiego |publisher=University of Łódź |language=pl |trans-title=Arabic digits when formatting centuries}}</ref>). On the other hand, in [[Turkish language|Turkish]] and some [[Central Europe|Central European]] Slavic languages, like most [[Germanic languages]], one writes "18." (with a period) before the local word for "century" (e.g. Turkish {{lang|tr|18. yüzyıl}}, Czech {{lang|cs|18. století}}).

[[File:Yeltsin-authograph-1988.gif|thumb|upright=1.1|[[Boris Yeltsin]]'s signature, dated 10 November 1988, rendered as 10.{{rn|XI}}.'88.]]

Mixed Roman and Arabic numerals are sometimes used in numeric representations of dates (especially in formal letters and official documents, but also on tombstones). The {{strong|month}} is written in Roman numerals, while the day is in Arabic numerals: "4.{{rn|VI}}.1789" and "{{rn|VI}}.4.1789" both refer unambiguously to 4 June 1789.

[[File:DarboLaikas.jpg|thumb|upright=0.9|left|Business hours table on a shop window in [[Vilnius]], Lithuania.]]

Roman numerals are sometimes used to represent the {{strong|days of the week}} in hours-of-operation signs displayed in windows or on doors of businesses,<ref>{{Cite web |title=Beginners latin |url=http://www.nationalarchives.gov.uk/latin/beginners/dating/default.htm |archive-url=https://web.archive.org/web/20131203092331/http://www.nationalarchives.gov.uk/latin/beginners/dating/default.htm |archive-date=3 December 2013 |access-date=1 December 2013 |website=nationalarchives.gov.uk}}</ref> and sometimes in railway and bus timetables. Monday, taken as the first day of the week, is represented by {{rn|I}}. Sunday is represented by {{rn|VII}}. The hours of operation signs are tables composed of two columns where the left column is the day of the week in Roman numerals and the right column is a range of hours of operation from starting time to closing time. In the example case (left), the business opens from 10 AM to 7 PM on weekdays, 10 AM to 5 PM on Saturdays and is [[Sunday shopping|closed on Sundays]]. Note that the listing uses 24-hour time.

[[File:S6002447 cropped.jpg|thumb|Sign at 17.9 km on route SS4 [[Via Salaria|Salaria]], north of Rome, Italy.]]

Roman numerals may also be used for [[floor numbering]].<ref>{{Cite web |title=Roman Arithmetic |url=http://turner.faculty.swau.edu/mathematics/materialslibrary/roman/ |archive-url=https://web.archive.org/web/20131122162120/http://turner.faculty.swau.edu/mathematics/materialslibrary/roman/ |archive-date=22 November 2013 |access-date=1 December 2013 |publisher=[[Southwestern Adventist University]]}}</ref><ref>{{Cite web |title=Roman Numerals History |url=http://romannumerals.info/roman-numerals-history/ |archive-url=https://web.archive.org/web/20131203091427/http://romannumerals.info/roman-numerals-history/ |archive-date=3 December 2013 |url-status=usurped |access-date=1 December 2013}}</ref> For instance, apartments in central [[Amsterdam]] are indicated as 138-{{rn|III}}, with both an Arabic numeral (number of the block or house) and a Roman numeral (floor number). The apartment on the ground floor is indicated as {{lang|nl|138-huis}}.

In Italy, where roads outside built-up areas have [[Milestone|kilometre signs]], major roads and motorways also mark 100-metre subdivisionals, using Roman numerals from {{rn|I}} to {{rn|IX}} for the smaller intervals. The sign {{sfrac|{{rn|IX}}|17}} thus marks 17.9&nbsp;km.

Certain romance-speaking countries use Roman numerals to designate assemblies of their national legislatures. For instance, the composition of the [[Italy|Italian]] [[Parliament of Italy|Parliament]] from 2018 to 2022 (elected in the [[2018 Italian general election]]) is called the [[Legislature XVIII of Italy|XVIII Legislature of the Italian Republic]] (or more commonly the "XVIII Legislature").

A notable exception to the use of Roman numerals in Europe is in Greece, where [[Greek numerals]] (based on the Greek alphabet) are generally used in contexts where Roman numerals would be used elsewhere.