View source for Roman numerals

'''Roman numerals''' are a [[numeral system]] of [[ancient Rome]] based on letters of the alphabet, which are combined to signify the sum (or in some cases, the difference) of their values. The first ten Roman numerals are:
:<math>\mathrm{I,\;II,\;III,\;IV,\;V,\;VI,\;VII,\;VIII,\;IX,\;X}</math>
The Roman numeral system is decimal<ref>Or more precisely, "a decimal system in which the number 5 is an auxiliary base" (Ifrah 200:193)</ref> but not directly [[Positional notation|positional]] and does not include a [[zero]]. It is a cousin of the [[Etruscan numerals]], and the letters derive from earlier non-alphabetical symbols; over time the Romans came to identify the symbols with letters of the [[Latin alphabet]]. The system was modified slightly during the [[Middle Ages]] to produce the system used today. 

Roman numerals are commonly used in numbered lists (such as the outline format of an article), clock faces, pages preceding the main body of a book, chord triads in music analysis, dated notices of copyright, months of the year, successive political leaders or children with identical names, and the numbering of annual events. See [[#Modern usage|modern usage]] below.

For arithmetic involving Roman numerals, see [[Roman arithmetic]] and [[Roman abacus]].

{{Table Numeral Systems}}
[[Image:Colosseum-Entrance LII.jpg|thumb|Entrance to section LII of the [[Colosseum]], with numerals still visible]]

== Symbols ==
Roman numerals are based on seven symbols: a stroke (identified with the letter I) for a unit, a chevron (identified with the letter V) for a five, a cross-stroke (identified with the letter X) for a ten, a C (identified as an abbreviation of ''Centum'') for a hundred, ''etc.'':
{| class="wikitable"
! Symbol
! Value
|-
| [[I]]
| 1 ([[1 (number)|one]]) ({{lang|la|''unus''}})
|-
| [[V]]
| 5 ([[5 (number)|five]]) ({{lang|la|''quinque''}})
|-
| [[X]]
| 10 ([[10 (number)|ten]]) ({{lang|la|''decem''}})
|-
| [[L]]
| 50 ([[50 (number)|fifty]]) ({{lang|la|''quinquaginta''}})
|-
| [[C]]
| 100 ([[100 (number)|one hundred]]) ({{lang|la|''centum''}})
|-
| [[D]]
| 500 ([[500 (number)|five hundred]]) ({{lang|la|''quingenti''}})
|-
| [[M]]
| 1000 ([[1000 (number)|one thousand]]) ({{lang|la|''mille''}})
|}

Symbols are iterated to produce multiples of the decimal (1, 10, 100, 1000) values, with V, L, D substituted for a multiple of five, and the iteration continuing: I "1", II "2", III "3", V "5", VI "6", VII "7", etc., and the same for other bases: X "10", XX "20", XXX "30", L "50", LXXX "80"; CC "200", DCC "700", ''etc.'' At the fourth iteration, a ''subtractive principle'' may be employed, with the base placed ''before'' the higher base: IIII or IV "4", VIIII or IX "9", XXXX or XL "40", LXXXX or XC "90", CCCC or CD "400", DCCCC or CM "900". 

The Romans only used what is called capital (upper case) letters in modern usage. In the Middle Ages, [[Lower case|minuscule]] (lower case) letters were developed, and these are commonly used for Roman numerals: i, ii, iii, iv, ''etc.'' Also in medieval use was the substitution of ''j'' for a final ''i'' to end numbers, such as ''iij'' for 3 or ''vij'' for 7. This was not a separate letter, but merely a [[Swash (typography)|swash]] variant of ''i.'' It is used today, especially in [[medical prescription]]s, to prevent tampering with the numbers after they are written.{{Citation needed|date=August 2009}} 

For large numbers (4000 and above), a bar can be placed above a base numeral, or parentheses placed around it, to indicate [[multiplication]] by 1000, although the Romans themselves often just wrote out the "M"s:<ref>[http://www.web40571.clarahost.co.uk/roman/howtheywork.htm#larger Roman numerals: How they work: Larger numbers]</ref>
* {{overline|V}} or (V) for [[5000 (number)|five thousand]]
* {{overline|X}} or (X) for [[10000 (number)|ten thousand]]
* {{overline|L}} or (L) for fifty thousand
* {{overline|C}} or (C) for [[100000 (number)|one hundred thousand]]
* {{overline|D}} or (D) for five hundred thousand
* {{overline|M}} or (M) for [[1000000 (number)|one million]]

The parentheses are more versatile; (II) is synonymous with MM, but {{overline|II}} is not found.

The basic multiples of Roman numerals thus follow a pattern:
{| class="wikitable" style="font-family: monospace"
! !!×1 !!×2 !!×3 !!×4 !!×5 !!×6 !!×7 !!×8 !!×9 
|-
!Ones
| I || II || III || IV || V || VI || VII || VIII || IX
|-
!Tens
| X || XX || XXX || XL || L || LX || LXX || LXXX || XC
|-
!Hundreds
| C || CC || CCC || CD || D || DC || DCC || DCCC || CM
|-
!Thousands
| M || MM || MMM || {{overline|IV}} || {{overline|V}} || {{overline|VI}} || {{overline|VII}} || {{overline|VIII}} || {{overline|IX}}
|-
!Ten thousands
| {{overline|X}} || {{overline|XX}} || {{overline|XXX}} || {{overline|XL}} || {{overline|L}} || {{overline|LX}} || {{overline|LXX}} || {{overline|LXXX}} || {{overline|XC}}
|-
! Hundred thousands
| {{overline|C}} || {{overline|CC}} || {{overline|CCC}} || {{overline|CD}} || {{overline|D}} || {{overline|DC}} || {{overline|DCC}} || {{overline|DCCC}} || {{overline|CM}}
|}

A practical way to write a Roman number is to consider the modern [[Arabic numeral]] system, and separately convert the thousands, hundreds, tens, and ones as given in the chart above. So, for instance, 1234 may be thought of as "one thousand and two hundreds and three tens and four", obtaining M (one thousand) + CC (two hundreds) + XXX (thirty) + IV (four), for MCCXXXIV. Thus eleven is XI (ten and one), 32 is XXXII (thirty and two) and 2009 is MMIX (two thousand and nine). Note that the subtractive principle is not extended beyond the chart, and IL is ''not'' used for 49, which can only be forty (XL) and nine (IX), or XLIX.

== Origins ==
Although the Roman numerals are now written with letters of the Roman alphabet, they were originally independent symbols. The [[Etruscans]], for example, used I Λ X {{unicode|⋔}} 8 ⊕ for I V X L C M, of which only I and X happened to be letters in their alphabet. One [[folk etymology]] has it that the V represented a hand, and that the X was made by placing two Vs on top of each other, one inverted. However, the Etrusco-Roman numerals actually appear to derive from notches on [[tally sticks]], which continued to be used by [[Italy|Italian]] and [[Dalmatia]]n shepherds into the 19th century.<ref>Georges Ifrah, ''The Universal History of Numbers: From Prehistory to the Invention of the Computer.'' Translated by David Bellos, E. F. Harding, Sophie Wood, Ian Monk. John Wiley & Sons, 2000.</ref>

Thus, I descends not from the letter I but from a notch scored across the stick. Every fifth notch was double cut (i.e. {{unicode|⋀}}, {{unicode|⋁}}, {{unicode|⋋}}, {{unicode|⋌}}, ''etc.''), and every tenth was cross cut (X), IIIIΛIIIIXIIIIΛIIIIXII…, much like European [[tally marks]] today. This produced a positional system: ''Eight'' on a counting stick was eight tallies, IIIIΛIII, or the eighth of a longer series of tallies; either way, it could be abbreviated ΛIII (or VIII), as the existence of a Λ implies four prior notches. By extension, ''eighteen'' was the eighth tally after the first ten, which could be abbreviated X, and so was XΛIII. Likewise, number ''four'' on the stick was the I-notch that could be felt just before the cut of the Λ (V), so it could be written as either IIII or IΛ (IV). Thus the system was neither additive nor subtractive in its conception, but ''[[Ordinal number (linguistics)|ordinal]]''. When the tallies were transferred to writing, the marks were easily identified with the existing Roman letters I, V, X

The tenth V or X along the stick received an extra stroke. Thus 50 was written variously as N, И, K, Ψ, {{unicode|⋔}}, ''etc.'', but perhaps most often as a chicken-track shape like a superimposed V and I - {{unicode|ᗐ}}. This had flattened to {{unicode|⊥}} (an inverted T) by the time of [[Caesar Augustus|Augustus]], and soon thereafter became identified with the graphically similar letter L. Likewise, 100 was variously Ж, {{unicode|⋉}}, {{unicode|⋈}}, H, or as any of the symbols for 50 above plus an extra stroke. The form Ж (that is, a superimposed X and I) came to predominate. It was written variously as >I< or {{unicode|ƆIC}}, was then abbreviated to {{unicode|Ɔ}} or C, with C variant finally winning out because, as a letter, it stood for {{lang|la|''centum''}}, Latin for "hundred". 

The hundredth V or X was marked with a box or circle. Thus 500 was like a {{unicode|Ɔ}} superposed on a {{unicode|⋌}} or {{unicode|⊢}} — that is, like a Þ with a cross bar,— becoming <s>D</s> or Ð by the time of Augustus, under the graphic influence of the letter D. It was later identified ''as'' the letter D, perhaps as an abbreviation of {{lang|la|''demi-mille''}} "half-thousand"; this at least was the folk etymology given to it later on. 

Meanwhile, 1000 was a circled or boxed X: {{unicode|Ⓧ}}, {{unicode|⊗}}, ⊕, and by Augustinian times was partially identified with the Greek letter Φ ''phi''. In different traditions it then evolved along several different routes. Some variants, such as Ψ and ↀ, were historical dead ends, although folk etymology later identified D for 500 as graphically half of Φ for 1000 because of the CD variant. A third line, {{unicode|ↀ}}, survives to this day in two variants:
* One, {{unicode|CIƆ}}, led to the convention of using parentheses to indicate multiplication by a thousand: the original CIƆ = (I) 1000, then (III) for 3000, (V) 5000, (IX) 9000, (X) 10&nbsp;000, (L) 50&nbsp;000, (C) 100&nbsp;000, (D) 500&nbsp;000, (M) 1000&nbsp;000, ''etc.'' This was later extended to double parentheses, as in {{unicode|ↁ}} , {{unicode|ↂ}}, ''etc.'' See [[#Alternate forms|alternate forms]] below.
* In the other, {{unicode|ↀ}} became {{unicode|∞}} and {{unicode|⋈}}, eventually changing to M under the influence of the Latin word {{lang|la|''mille''}} "thousand".

== Zero ==
In  general, the number [[0 (number)|zero]] did not have its own Roman numeral, but a primitive form (''nulla'') was known by medieval [[computus|computists]] (responsible for calculating the date of [[Easter]]). They included zero (via the [[Latin]] word {{lang|la|''nulla''}} meaning "none") as one of nineteen [[epact]]s, or the age of the moon on March 22. The first three epacts were ''nulla'', xi, and xxii (written in [[Lower case|minuscule]] or lower case). The first known computist to use zero was [[Dionysius Exiguus]] in 525. Only one instance of a Roman numeral for zero is known. About 725, [[Bede]] or one of his colleagues used the letter [[N]], the initial of ''nulla'', in a table of epacts, all written in Roman numerals.

== Fractions ==
[[Image:Vecchi 003.jpg|thumb|left|150px|A {{lang|la|''[[triens]]''}} coin (1/3 or 4/12 of an {{lang|la|''as''}}). Note the four dots •••• indicating its value.]]
[[Image:Semisse.jpg|thumb|right|200px|A {{lang|la|''[[semis]]''}} coin (1/2 or 6/12 of an {{lang|la|''as''}}). Note the [[S]] indicating its value.]]

Though the Romans used a [[decimal]] system for [[whole number]]s, reflecting how they counted in Latin, they used a [[duodecimal]] system for [[rational number|fraction]]s, because the [[divisibility]] of twelve {{nowrap|1=(12 = 3 × 2 × 2)}} makes it easier to handle the common [[Fraction (mathematics)|fraction]]s of 1/3 and 1/4 than does a system based on ten {{nowrap|1=(10 = 2 × 5)}}. On [[coin]]s, many of which had values that were duodecimal fractions of the unit {{lang|la|''[[As (coin)|as]]''}}, they used a tally-like notational system based on twelfths and halves. A dot • indicated an {{lang|la|''uncia''}} "twelfth", the source of the English words ''inch'' and ''ounce''; dots were repeated for fractions up to five twelfths. Six twelfths (one half) was abbreviated as the letter [[S]] for {{lang|la|''semis''}} "half". ''Uncia'' dots were added to S for fractions from seven to eleven twelfths, just as tallies were added to V for whole numbers from six to nine. 

Each of these fractions had a name, which was also the name of the corresponding coin:

{| class="wikitable"
!Fraction
!Roman Numeral
!Name (nominative and genitive)
!Meaning
|-
| 1/12
| •
| {{lang|la|''[[Uncia (coin)|uncia, unciae]]''}}
| "ounce"
|-
| 2/12 = 1/6
| •• or ''':'''
| {{lang|la|''[[Sextans (coin)|sextans, sextantis]]''}}
| "sixth"
|-
| 3/12 = 1/4
| ••• or '''∴'''
| {{lang|la|''[[quadrans|quadrans, quadrantis]]''}}
| "quarter"
|-
| 4/12 = 1/3
| •••• or '''::'''
| {{lang|la|''[[triens|triens, trientis]]''}}
| "third"
|-
| 5/12
| ••••• or ''':'''•''':'''
| {{lang|la|''[[Quincunx (coin)|quincunx, quincuncis]]''}}
| "five-ounce" (''quinque unciae'' → ''quincunx'')
|-
| 6/12 = 1/2
| S
| {{lang|la|''[[semis|semis, semissis]]''}}
| "half"
|-
| 7/12
| S•
| {{lang|la|''[[septunx|septunx, septuncis]]''}}
| "seven-ounce" (''septem unciae'' → ''septunx'')
|-
| 8/12 = 2/3
| S•• or S''':'''
| {{lang|la|''[[Bes (coin)|bes, bessis]]''}}
| "twice" (as in "twice a third")
|-
| 9/12 = 3/4
| S••• or S''':'''•
| {{lang|la|''[[dodrans|dodrans, dodrantis]]''}}<br>'''or''' {{lang|la|''nonuncium, nonuncii''}}
| "less a quarter" (''de-quadrans'' → ''dodrans'')<br>'''or''' "ninth ounce" (''nona uncia'' → ''nonuncium'')
|-
| 10/12 = 5/6
| S•••• or S'''::'''
| {{lang|la|''[[dextans|dextans, dextantis]]''}}<br>'''or''' {{lang|la|''decunx, decuncis''}}
| "less a sixth" (''de-sextans'' → ''dextans'')<br>'''or''' "ten ounces" (''decem unciae'' → ''decunx'')
|-
| 11/12
| S••••• or S''':'''•''':'''
| {{lang|la|''[[deunx|deunx, deuncis]]''}}
| "less an ounce" (''de-uncia'' → ''deunx'')
|-
| 12/12 = 1
| I
| {{lang|la|''[[as (coin)|as, assis]]''}}
| "unit"
|}

The arrangement of the dots was variable and not necessarily linear. Five dots arranged like :·: (as on the face of a [[dice|die]]) are known as a [[quincunx]] from the name of the Roman fraction/coin. The Latin words ''sextans'' and ''quadrans'' are the source of the English words [[sextant]] and [[quadrant]].

Other Roman fractions include:
* 1/8 {{lang|la|'''''sescuncia, sescunciae'''''}} (from ''[[sesqui-]]'' + ''uncia'', i.e. 1½ uncias), represented by a sequence of the symbols for the semuncia and the uncia.
* 1/24 {{lang|la|'''''semuncia, semunciae'''''}} (from ''[[semi-]]'' + ''uncia'', i.e. ½ uncia), represented by several variant glyphs deriving from the shape of Greek letter [[sigma]] {{Unicode|Σ}}, one variant resembling the pound sign {{Unicode|£}} without the horizontal line(s) and another resembling Cyrillic letter {{Unicode|Є}}.
* 1/36 {{lang|la|'''''binae sextulae, binarum sextularum'''''}} ("two sextulas") or {{lang|la|'''''[[duella]], duellae'''''}}, represented by ƧƧ, a sequence of two reversed S.
* 1/48 {{lang|la|'''''sicilicus, sicilici'''''}}, represented by Ɔ, a reversed C.
* 1/72 {{lang|la|'''''sextula, sextulae'''''}} (1/6 of an uncia), represented by Ƨ, a reversed S.
* 1/144 {{lang|la|'''''dimidia sextula, dimidiae sextulae'''''}} ("half a sextula"), represented by ƻ, a reversed S crossed by a horizontal line.
* 1/288 {{lang|la|'''''scripulum, scripuli'''''}} (a [[scruple]]), represented by the symbol {{Unicode|℈}}.
* 1/1728 {{lang|la|'''''siliqua, siliquae'''''}}, represented by a symbol resembling closing guillemets ».

== IIII vs IV ==
The notation of Roman numerals has varied through the centuries. Originally, it was common to use IIII to represent ''four'', because IV represented the [[Roman mythology|Roman god]] [[Jupiter (mythology)|Jupiter]], whose Latin name, IVPPITER, begins with IV. The [[subtractive notation]] (which uses IV instead of IIII) has become the standard notation only in modern times. For example, [[Forme of Cury]], a manuscript from 1390, uses IX for ''nine'', but IIII for ''four''. Another document in the same manuscript, from 1381, uses IV and IX. A third document in the same manuscript uses IIII, IV, and IX. Constructions such as IIIII for ''five'', IIX for ''eight'' or VV for ''10'' have also been discovered. [[Subtractive notation]] arose from regular Latin usage: the number 18 was {{lang|la|''duodeviginti''}} or “two from twenty”; the number 19 was {{lang|la|''undeviginti''}} or "one from twenty". The use of subtractive notation increased the complexity of performing [[Roman arithmetic]], without conveying the benefits of a full [[positional notation]] system.

[[Image:AdmiraltyArchLondonCloseup.jpg|thumb|An inscription on [[Admiralty Arch]], London. The numeral translates to 1910.]]
Likewise, on some buildings it is possible to see MDCCCCX, for example, representing 1910 instead of MCMX – notably [[Admiralty Arch]] in [[London]]. The Leader Building in [[Cleveland, Ohio]], at the corner of Superior Avenue and E.6th Street, is marked MDCCCCXII, representing 1912 instead of MCMXII. Another notable example is on [[Harvard Medical School]]'s Gordon Hall, which reads MDCCCCIIII for 1904 instead of MCMIV. In [[Dubrovnik]], [[Croatia]], a commemorative inscription marking the 1000th anniversary of [[Tomislav I of Croatia|King Tomislav]]’s coronation (Croatia’s first King), appears as DCCCCXXV - MDCCCCXXV (925 -1925).

=== Calendars and clocks ===
{{Original research|date=August 2009}}
[[Image:Greenwich clock 1-manipulated.jpg|thumb|The [[Shepherd gate clock]] with Roman numbers up to XXIII (and 0), in Greenwich]]

Clock faces that are labeled using Roman numerals conventionally show IIII for four o'clock and IX for nine o'clock, using the subtractive principle in one case and not the other. There are many suggested explanations for this, several of which may be true:

* [[Louis XIV of France|Louis XIV]], king of France, who preferred IIII over IV, ordered his clockmakers to produce clocks with IIII and not IV, and thus it has remained.<ref>W.I. Milham, ''Time & Timekeepers'' (New York: Macmillan, 1947) p. 196</ref>
* Using the standard numerals, two sets of figures would be similar and therefore confusable by children and others unused to reading clockfaces: IV and the VI; and IX and XI. Since the first pair are additionally upside down on the face, an added level of confusion would be introduced. It is used to make greater character distinction between them by using IIII and VI
* The four-character form IIII creates a visual symmetry with the VIII on the other side, which the two-character IV would not.
* With IIII, the number of symbols on the clock totals twenty I's, four V's, and four X's, so clock makers need only a single mold with a V, five I's, and an X in order to make the correct number of numerals for their clocks: VIIIIIX. This is cast four times for each clock and the twelve required numerals are separated:
** V IIII IX 
** VI II IIX
** VII III X
** VIII I IX
:The IIX and one of the IX’s are rotated 180° to form XI and XII. The alternative with IV uses seventeen I's, five V's, and four X's, requiring the clock maker to have several different molds.
* Only the I symbol would be seen in the first four hours of the clock, the V symbol would only appear in the next four hours, and the X symbol only in the last four hours. This would add to the clock's radial symmetry.
* Many clocks use IIII because that was the tradition established by the earliest surviving clock, the [[Wells Cathedral clock]] built between 1386 and 1392. It used IIII because that was the typical method used to denote 4 in contemporary manuscripts (as iiij or iiii). That clock had an asymmetrical 24-hour dial and used Arabic numerals for a minute dial and a moon dial, so theories depending on a symmetrical 12-hour clock face do not apply.<ref>Paul Lewis, [http://www.web40571.clarahost.co.uk/roman/clockface.htm Clocking the fours: A new theory about IIII]</ref>

== Subtractive principle == <!-- N.B. this is linked internally so if you change the section header change the internal links -->
Generally, Roman numerals are written in descending order from left to right, and are added sequentially, for example MMVI (2006) is interpreted as 1000 + 1000 + 5 + 1.

Certain combinations employ a subtractive principle, which specifies that where a symbol of smaller value precedes a symbol of larger value, the smaller value is subtracted from the larger value, and the result is added to the total. For example, in MCMXLIV (1944), the symbols C, X and I each precede a symbol of higher value, and the result is interpreted as 1000 plus (1000 minus 100) plus (50 minus 10) plus (5 minus 1).

A numeral for 10<sup><var>n</var></sup> (I, X, or C) may not precede a numeral larger than 10<sup><var>n</var>+1</sup>, where <var>n</var> is an [[integer]].{{Citation needed|date=August 2009}} That is, I may precede V and X, but not L or C; X may precede L or C, but not D or M. The numerals 5×10<sup><var>n</var></sup> (V, L, or D) may not be followed by a numeral of greater or equal value.{{Citation needed|date=August 2009}} Any symbol that appears more than once consecutively may not be followed by a symbol of larger value.

== Modern usage ==
[[Image:CuttySarkRomNum.jpg|thumb|Roman numbers on stern of ''[[Cutty Sark]]'', [[Greenwich]]]]
Roman numerals remained in common use until about the 14th century, when they were replaced by [[Hindu-Arabic numerals]] (thought to have been introduced to Europe from [[al-Andalus]], by way of [[Arab]] traders and arithmetic treatises, around the 11th century). The Roman number system is generally regarded as obsolete in modern usage, but is still seen occasionally. Classical numbering is often used to suggest importance or timelessness, or in other cases where an alternate numbering system is useful for clarity. Examples of their current use include:
* Names of monarchs and Popes, e.g. [[Elizabeth II of the United Kingdom|Elizabeth II]], [[Pope Benedict XVI|Benedict XVI]]. These are [[ordinal]] numbers; e.g. "II" is pronounced "the second".
* The year of production of television shows and films.
* Hour marks on some clockfaces and timepieces.
* The year of construction on some building faces and [[cornerstone]]s.
* Publication dates of books (particularly older ones); page numbering of preliminary pages; volume numbers on spines and chapter numbers.
* [[Film series]] and [[sequel]]s of [[novel]]s and [[video game]]s (such as [[Final Fantasy]]), typically emulating use in older books.
* [[Outline (summary)|Outline]]s use I, II, III and i, ii, iii as part of their organizational structure.
* A recurring grand event, such as the [[Olympic Games]], [[Super Bowl]], [[WrestleMania]], or the [[Sprint All-Star Race]].
* Historic events, such as [[World War II]]
* Names of Army [[Corps]].
* [[Crossword]] puzzle clues, particularly [[cryptic crossword]]s.
* Names of [[cranial nerves]].
* [[Guitar]] chord diagrams.
* Parts of [[law]]s, such as Titles (e.g. [[Civil Rights Act of 1964]]) or Schedules (e.g. [[Controlled Substances Act]]).
* Sports teams, indicating the number of players in the squad. In [[rugby union]], the 1st XV of a particular club would be the 1st and best team the club has, likewise for the XIII in [[rugby league]], and XI for [[Association football|football (soccer)]], [[field hockey]] and [[cricket]].
* Some countries use Roman numerals to number centuries (instead of "''18th century''", "''XVIII century''" is used). This is uncommon in the English-speaking world.{{Citation needed|date=October 2009}}
* [[Callsigns_in_North_America#United_States|Call signs]] of some American television stations (usually based on the station's channel number; such as [[WXII-TV|W'''XII''']], [[KXII-TV|K'''XII''']], [[WXIX|W'''XIX''']], [[WPVI-TV|WP'''VI''']], etc.)
*[[RAF]] squadrons have two names, there's the standard number name (which is most commonly used) and the Roman numeral name (e.g. [[No. 15 Squadron RAF]] or [[No. XV Squadron RAF]]). 

Sometimes the numerals are written using lower-case letters (thus: i, ii, iii, iv, etc.), particularly if numbering paragraphs or sections within chapters, or for the pagination of the front matter of a book.

Undergraduate degrees at British universities are generally graded using I, IIi, IIii, III for first, upper second (often pronounced "two one"), lower second (often pronounced "two two") and third class respectively.

In [[chemistry]], Roman numerals were formerly used to denote the [[periodic table group|group]] in the [[periodic table of the elements]]. But there was not international agreement as to whether the group of metals which dissolve in water should be called Group IA or IB, for example, so although references may use them, the international norm has recently switched to Arabic numerals. However, Roman numerals are still used in the [[IUPAC nomenclature of inorganic chemistry]], for the [[oxidation number]] of [[cation]]s which can take on several different positive charges. For example, FeO is iron(II) oxide and Fe<sub>2</sub>O<sub>3</sub> is iron(III) oxide.  In contrast, Arabic numerals are used to denote the formal [[oxidation state]] (which is not always the same as the oxidation number) of positively or negatively charged atoms.  They are also used for naming [[Phase (matter)|phases]] of [[Polymorphism (materials science)|polymorphic]] [[crystal]]s, such as [[ice]].

In [[astronomy]], the [[natural satellite]]s or "moons" of the [[planet]]s are traditionally designated by capital Roman numerals, at first by order from the center of the planet, as the four [[Galilean moons|Galilean satellite]]s of [[Jupiter]] are numbered, and later by order of discovery; e.g., [[Callisto (moon)|Callisto]] was "Jupiter IV" or "J IV". Notably, the notation IV was mostly disused by the Romans for its similarity to the first two letters of Jupiter. With recent discoveries—Jupiter currently has 63 known satellites—as well as computerization, this is somewhat disparaged for the minor worlds, at least in computerized listings.

[[Science fiction]], and not astronomy ''per se'', has adopted the use for numbering the planets around a star; e.g., Planet Earth is called "[[Sun|Sol]] III".

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

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

=== Music theory ===
In [[music theory]], while [[scale degree]]s are typically represented with Arabic numerals, often modified with a [[caret]] or [[circumflex]], the [[triad (music)|triad]]s that have these degrees as their roots are often identified by Roman numerals (as in [[chord symbol]]s). See also [[diatonic function]]s. Upper-case Roman numerals indicate major triads while lower-case Roman numerals indicate minor triads, as the following chart illustrates. Lower-case Roman numerals with a [[degree symbol]] indicate [[diminished chord|diminished]] triads. For example, in the [[major mode]] the triad on the seventh scale degree, the leading tone triad is diminished.

Also in music theory, individual strings of stringed instruments, such as the [[violin]], are often denoted by Roman numerals, with higher numbers denoting lower strings.  For example I signifies the E string on the violin and the A string on the [[viola]] and [[cello]], these being the highest strings, respectively, on each instrument.  They are also sometimes used to signify [[Violin#positions|position]].  In this case, the number in Roman numerals corresponds with the position number.  For example, III means third position and V means fifth.

{| class="wikitable"
|'''Roman numeral''' ||align=center| I ||align=center| ii ||align=center| iii ||align=center| IV ||align=center| V ||align=center| vi ||align=center| vii<sup>°</sup>
|-
|'''Scale degree <br />(major mode)''' || [[tonic (music)|tonic]] || [[supertonic]] || [[mediant]] || [[subdominant]] || [[dominant (music)|dominant]] || [[submediant]] || [[leading tone]]
|}

{| class="wikitable"
|'''Roman numeral''' ||align=center| i ||align=center| ii<sup>°</sup> ||align=center| ({{music|flat}})III ||align=center| iv ||align=center| v ||align=center| ({{music|flat}})VI ||align=center| ({{music|flat}})VII ||align=center| vii<sup>°</sup>
|-
|'''Scale degree <br />(minor mode)''' || [[tonic (music)|tonic]] || [[supertonic]] || [[mediant]] || [[subdominant]] || [[dominant (music)|dominant]] || [[submediant]] || [[subtonic]] || [[leading tone]]
|}

=== Modern non-English-speaking usage ===
The above uses are customary for English-speaking countries. Although many of them are also maintained in other countries, those countries have additional uses for Roman numerals that are not normally employed in English-speaking regions.

The [[French language|French]], [[Hungarian language|Hungarian]], [[Italian language|Italian]], [[Portuguese language|Portuguese]], [[Polish language|Polish]], [[Romanian language|Romanian]], [[Russian language|Russian]], [[Spanish language|Spanish]] and [[Catalan language|Catalan]] languages use capital Roman numerals to denote '''centuries'''. For example, ''XVIII'' refers to the eighteenth century, so as to avoid confusion between the ''18th century'' and the ''1800s''. (The Italians also take the opposite approach, basing names of centuries on the digits of the years; {{lang|it|''[[quattrocento]]''}} for example is a common Italian name for {{lang|it|''secolo XV''}}, the fifteenth century.) Some scholars in English-speaking countries have adopted the former method.

In [[Italy]], [[Poland]], [[Russia]], [[Central Europe]], and in [[Portuguese language|Portuguese]], [[Romanian language|Romanian]] and [[Serbian language|Serbian]] languages, mixed Roman and Arabic numerals are used to record '''dates''' (usually on tombstones, but also elsewhere, such as in formal letters and official documents). Just as an old clock recorded the hour by Roman numerals while the minutes were measured in [[Arabic numerals]], the month is written in Roman numerals while the day is in Arabic numerals: 14.VI 1789 is 14 June 1789. This is how dates are inscribed on [[Kremlin Wall Necropolis|the walls of the Kremlin]], for example. This method has the advantage that days and months are not confused in rapid note-taking, and that any range of days or months can be expressed without confusion. For instance, V-VIII is May to August, while 1.V - 31.VIII is 1 May to 31 August.

In [[Eastern Europe]], especially the [[Baltic Sea|Baltic]] nations, Roman numerals are used to represent the days of the week in hours-of-operation signs displayed in windows or on doors of businesses. Monday is represented by ''I'', which is the initial day of the [[week]]. Sunday is represented by ''VII'', which is the final day of the week. 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. The following example hours-of-operation table would be for a business whose hours of operation are 9:30 AM to 5:30 PM on Mondays, Wednesdays, and Thursdays; 9:30 AM to 7:00 PM on Tuesdays and Fridays; and 9:30 AM to 1:00 PM on Saturdays; and which is closed on Sundays.
{| class="wikitable"
|-
| align=center style="font-family: 'Times New Roman', Times" | I
| align=center | 9:30&ndash;17:30
|-
| align=center style="font-family: 'Times New Roman', Times" | II
| align=center | 9:30&ndash;19:00
|-
| align=center style="font-family: 'Times New Roman', Times" | III
| align=center | 9:30&ndash;17:30
|-
| align=center style="font-family: 'Times New Roman', Times" | IV
| align=center | 9:30&ndash;17:30
|-
| align=center style="font-family: 'Times New Roman', Times" | V
| align=center | 9:30&ndash;19:00
|-
| align=center style="font-family: 'Times New Roman', Times" | VI
| align=center | 9:30&ndash;13:00
|-
| align=center style="font-family: 'Times New Roman', Times" | VII
| align=center | &mdash;
|}

[[Image:Resistor symbol 5W GOST.svg|right|100px|thumb|A five–watt resistor as per GOST 2.728–74.]]
In [[Commonwealth of Independent States|CIS]] countries, capital Roman numerals I, II and V still are sometimes used according to the regional standard [[GOST]] 2.728–74 (2002), to specify rated [[resistor]] power (in watts) in schematic symbols by inscribing the numeral along inside the symbol rectangle.

Since the French use capital Roman numerals to refer to the quarters of the year (''III'' is the third quarter), and this has become the norm in some European standards organisation, the mixed Roman–Arabic method of recording the date has switched to lowercase Roman numerals in many circles, as ''4-viii-1961''. ([[International Organization for Standardization|ISO]] has since specified that dates should be given in all Arabic numerals, in [[ISO 8601]] formats.)

In [[geometry]], Roman numerals are often used to show lines of equal length.<!--Should this be in the previous section? Or are we talking about geometry in a particular non-English-speaking location??-->

In [[Poland]], [[Romania]], [[Serbia]] and other European countries to lesser extent, Roman numerals are used for [[floor numbering]]. Likewise apartments in central [[Amsterdam]] are indicated as ''138-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 [[Poland]], Roman numerals are used for ordinals in names of some institutions. In particular high schools ("{{lang|pl|V Liceum Ogólnokształcące w Krakowie}}" - ''5th High School in Kraków''), tax offices ("{{lang|pl|II Urząd Skarbowy w Gdańsku}}" - ''2nd Office of Treasury in Gdańsk'') and courts ("{{lang|pl|I Wydział Cywilny Sądu Okręgowego}}" - ''District Court, 1st Civil Division'') - use Roman numerals. Institutions that use "{{lang|pl|Institution nr N}}" notation always use Arabic numerals. These include elementary ("{{lang|pl|Szkoła Podstawowa nr 5}}") and middle schools ("{{lang|pl|Gimnazjum nr 5}}").

Roman numerals are rarely used in [[Asia]]. The [[motion picture rating system]] in [[Hong Kong]] uses categories I, IIA, IIB, and III based on Roman numerals.

== Alternate forms ==

In the Middle Ages, Latin writers used a horizontal line above a particular numeral to represent one thousand times that numeral, and additional vertical lines on both sides of the numeral to denote one hundred times the number, as in these examples:

* {{overline|I}} for [[1000 (number)|one thousand]]
* {{overline|V}} for [[5000 (number)|five thousand]]
* |{{overline|I}}| for [[100000 (number)|one hundred thousand]]
* |{{overline|V}}| for five hundred thousand

The same overline was also used with a different meaning, to clarify that the characters were numerals. Sometimes both underline and overline were used, e.&nbsp;g. <u>{{overline|MCMLXVII}}</u>, and in certain ([[serif]]) [[typeface]]s, particularly [[Times New Roman]], the capital letters when used without spaces simulates the appearance of the under/over bar, e.g. <span style="font-family:times new roman, times, serif">MCMLXVII</span>.  

Sometimes 500, usually D, was written as {{unicode|I}} followed by an ''apostrophus'' or ''apostrophic C'' (which resembles a backwards C, i.e. {{unicode|Ɔ}}), while 1,000, usually M, was written as {{unicode|CIƆ}}. This is believed to be a system of encasing numbers to denote thousands (imagine the Cs as parentheses). This system has its origins from Etruscan numeral usage. The D and M symbols to represent 500 and 1,000 were most likely derived from {{unicode|IƆ}} and {{unicode|CIƆ}}, respectively.

[[Image:Roman numerals Bungus 1584-1585.png|thumb|Roman numerals, [[16th century]]]]

An extra {{unicode|Ɔ}} denoted 500, and multiple extra {{unicode|Ɔ}}s are used to denote 5,000, 50,000, etc. For example:

{| class="wikitable Unicode"
|-
!Base number
|align=right|&nbsp;
|align=right|CIƆ = 1,000
|align=right|CCIƆƆ = 10,000
|align=right|CCCIƆƆƆ = 100,000
|-
!1 extra Ɔ
|align=right|IƆ = 500
|align=right|CIƆƆ = 1,500
|align=right|CCIƆƆƆ = 10,500
|align=right|CCCIƆƆƆƆ = 100,500
|-
!2 extra Ɔs
|align=right|IƆƆ = 5,000
|align=right|&nbsp;
|align=right|CCIƆƆƆƆ = 15,000
|align=right|CCCIƆƆƆƆƆ = 105,000
|-
!3 extra Ɔs
|align=right|IƆƆƆ = 50,000
|align=right|&nbsp;
|align=right|&nbsp;
|align=right|CCCIƆƆƆƆƆƆ = 150,000
|}

Sometimes {{unicode|CIƆ}} was reduced to a [[lemniscate]] symbol ({{unicode|ↀ}}) for denoting 1,000. [[John Wallis]] is often credited for introducing this symbol to represent infinity ({{unicode|∞}}), and one conjecture is that he based it on this usage, since 1,000 was [[hyperbole|hyperbolically]] used to represent very large numbers. Similarly, 5,000 ({{unicode|IƆƆ}}) was reduced to {{unicode|ↁ}}; and 10,000 ({{unicode|CCIƆƆ}}) was reduced to {{unicode|ↂ}}.

In medieval times, before the letter ''j'' emerged as a distinct letter, a series of letters ''i'' in Roman numerals was commonly ended with a flourish; hence they actually looked like ''ij'', ''iij'', ''iiij'', etc. This proved useful in preventing fraud, as it was impossible, for example, to add another ''i'' to ''vij'' to get ''viij''. This practice is now merely an [[antiquarian]]'s note; it is never used.{{Citation needed|date=August 2009}}

=== Medieval Roman numerals ===
Most uniquely, during the Middle Ages there came about a unique, more comprehensive shorthand for writing Roman numerals, called today the "medieval Roman numerals." This system used almost every other letter of the Roman alphabet to stand as abbreviations for more longhand numbers (usually those that consisted of repetitions of the same symbol). They are still listed today in most dictionaries, although through disfavor are primarily out of use.<ref>Capelli, A. ''Dictionary of Latin Abbreviations.'' 1912.</ref>

{|class="sortable wikitable"
!Modern<br>number
!Medieval<br>abbreviation
!Notes
|-
|5
|A
|Resembles an upside-down V. Also said to equal 500.
|-
|6
|ↅ
|Either a ligature of VI, or the Greek letter [[Stigma (letter)|stigma]] (Ϛ), having the same  numerical value.<ref name="PropN3218">Perry, David J. [http://std.dkuug.dk/jtc1/sc2/wg2/docs/N3218.pdf Proposal to Add Additional Ancient Roman Characters to UCS].</ref>
|-
|7
|S, Z
|Presumed abbreviation of ''septem'', Latin for 7.
|-
|11
|O
|Presumed abbreviation of (e.g.) ''onze'', French for 11.
|-bgcolor="#ffdddd"
|40
|F
|Presumed abbreviation of English ''forty''.
|-
|70
|S
|Also could stand for 7, and has same etymology.
|-bgcolor="#ffdddd"
|80
|R
|
|-
|90
|N
|Presumed abbreviation of ''nonaginta'', Latin for 90.
|-bgcolor="#ddddff"
|150
|Y
|Possibly derived from the lowercase y's shape.
|-
|151
|K
|This unusual abbreviation's origin is unknown; it has also been said to stand for 250.
|-bgcolor="#ffdddd"
|160
|T
|Possibly derived from Greek ''tetra'', as 4 x 40 = 160.
|-bgcolor="#ddddff"
|200
|H
|
|-bgcolor="#ddddff"
|250
|E
|
|-bgcolor="#ddddff"
|300
|B
|
|-bgcolor="#ddddff"
|400
|P, G
|
|-
|500
|Q
|Redundant with D, abbreviation for ''quingenti'', Latin for 500.
|-
|800
|W
|More properly, the Greek [[ω]], as W was a fairly new creation. Carried over from [[Gothic alphabet|Gothic]].
|-
|900
|ĵ, ↑
|Resembled a crooked up arrow. Carried over from [[Gothic alphabet|Gothic]].
|-
|2000
|Z
|
|}

== Modern Roman numerals ==
Some "modern" Roman numerals, post-[[Victorian era]], are shown below:
{| class="wikitable"
!Standard
!Arabic
!Notes
|-
|none
|[[0 (number)|0]]
|N for ''nulla'' was used at least once (by [[Bede]] about 725).
|-
|I
|[[1 (number)|1]]
|
|-
|II
|[[2 (number)|2]]
|
|-
|III
|[[3 (number)|3]]
|
|-
|IV
|[[4 (number)|4]]
|IIII is still used on clock and [[Tarot card games|Tarot card]] faces. See [[#Calendars and clocks|Calendars and clocks]] above.
|-
|V
|[[5 (number)|5]]
|IIIII was used rarely in the Middle Ages.
|-
|VI
|[[6 (number)|6]]
|
|-
|VII
|[[7 (number)|7]]
|
|-
|VIII
|[[8 (number)|8]]
|IIX was used rarely in the Middle Ages.
|-
|IX
|[[9 (number)|9]]
|
|-
|X
|[[10 (number)|10]]
|VV was used rarely in the Middle Ages.
|-
|XI
|[[11 (number)|11]]
|
|-
|XII
|[[12 (number)|12]]
|
|-
|XIII
|[[13 (number)|13]]
|
|-
|XIV
|[[14 (number)|14]]
|
|-
|XV
|[[15 (number)|15]]
|
|-
|XVI
|[[16 (number)|16]]
|
|-
|XVII
|[[17 (number)|17]]
|
|-
|XVIII
|[[18 (number)|18]]
|
|-
|XIX
|[[19 (number)|19]]
|
|-
|XX
|[[20 (number)|20]]
|
|-
|XXI
|[[21 (number)|21]]
|
|-
|XXV
|[[25 (number)|25]]
|
|-
|XXX
|[[30 (number)|30]]
|
|-
|XXXV
|[[35 (number)|35]]
|
|-
|XL
|[[40 (number)|40]]
|
|-
|XLV
|[[45 (number)|45]]
|
|-
|XLIX
|[[49 (number)|49]]
|Per rule [[#Subtractive_principle|above]], IL would not be generally accepted.
|-
|L
|[[50 (number)|50]]
|
|-
|LX
|[[60 (number)|60]]
|
|-
|LXIX
|[[69 (number)|69]]
|
|-
|LXX
|[[70 (number)|70]]
|The abbreviation for the [[Septuagint]]
|-
|LXXVI
|[[76 (number)|76]]
|
|-
|LXXX
|[[80 (number)|80]]
|
|-
|XC
|[[90 (number)|90]]
|
|-
|XCIX
|[[99 (number)|99]]
|As opposed to the "shortcut" way IC seen [[#Subtractive principle|above]].
|-
|C
|[[100 (number)|100]]
|This is the origin of using the slang term "C-bill" or "C-note" for "[[U.S. hundred dollar bill|$100 bill]]".
|-
|CL
|[[150 (number)|150]]
|
|-
|CC
|[[200 (number)|200]]
|
|-
|CCC
|[[300 (number)|300]]
|
|-
|CD
|[[400 (number)|400]]
|
|-
|D
|[[500 (number)|500]]
|
|-
|DC
|[[600 (number)|600]]
|
|-
|DCLXVI
|[[666 (number)|666]]
|Using every symbol except M in descending order gives the [[Number of the Beast (numerology)|beast number]].
|-
|DCC
|[[700 (number)|700]]
|
|-
|DCCC
|[[800 (number)|800]]
|
|-
|CM
|[[900 (number)|900]]
|
|-
|M
|[[1000 (number)|1,000]]
|
|-
|MCDXLIV
|[[1000 (number)|1,444]]
|Smallest [[pandigital number]] (each symbol is used)
|-
|MDCLXVI
|[[1000 (number)|1,666]]
|Largest efficient pandigital number (each symbol occurs exactly once)
|-
|MDCCCLXXXVIII
|[[1000 (number)|1,888]]
|Longest number when written (excluding multiple M's)
|-
|MCMXC
|[[1990 (number)|1,990]]
|Shortcuts like XMM and MXM disagree with the rule stated [[#Subtractive principle|above]]
|-
|MCMXCVII
|[[1997 (number)|1,997]]
|-
|MCMXCIX
|[[1000 (number)|1,999]]
|Shortcuts like IMM and MIM disagree with the rule stated [[#Subtractive principle|above]]
|-
|MM
|[[2000 (number)|2,000]]
|
|-
|MMI
|2,001
|
|-
|MMIX
|2,009
|
|-
|MMD
|2,500
|
|-
|MMM
|[[3000 (number)|3,000]]
|
|-
|{{overline|IV}}
|[[4000 (number)|4,000]]
|sometimes MMMM{{Citation needed|date=May 2008}} or M{{overline|V}}
|-
|{{overline|V}}
|[[5000 (number)|5,000]]
|
|-
|{{overline|V}}MDCLXVI
|[[6000 (number)|6,666]]
|This number uses every symbol up to {{overline|V}} once.
|-
|{{overline|X}}
|[[10000 (number)|10,000]]
|
|-
|{{overline|L}}
|[[50000 (number)|50,000]]
|
|-
|{{overline|C}}
|[[100000 (number)|100,000]]
|
|-
|{{overline|D}}
|500,000
|
|-
|{{overline|M}}
|[[1,000,000 (number)|1,000,000]]
|
|}

An accurate way to write large numbers in Roman numerals is to handle first the thousands, then hundreds, then tens, then units.
<br>Example: the number 1988.
<br>One thousand is M, nine hundred is CM, eighty is LXXX, eight is VIII. 
<br>Put it together: MCMLXXXVIII.

=== Unicode ===
[[Unicode]] has a number of characters specifically designated as Roman numerals, as part of the ''Number Forms''<ref name="UnicodeChart" >[http://www.unicode.org/charts/PDF/U2150.pdf Unicode Number Forms]</ref> range from U+2160 to U+2188. This range includes both upper- and lowercase numerals, as well as pre-combined [[glyphs]] for numbers up to 12 ({{unicode|Ⅻ}} or XII), mainly intended for the clock faces for [[compatibility]] with large East-Asian character sets such as [[JIS X 0213]]<!--others?--> that provide these characters. The pre-combined glyphs should only be used to represent the individual numbers where the use of individual glyphs is not wanted, and not to replace compounded numbers. Additionally, glyphs exist for archaic<ref name="UnicodeChart"/> forms of 1000, 5000, 10,000, large reversed C ({{unicode|Ɔ}}), late 6 ({{Unicode|ↅ}}, similar to Greek [[Stigma (letter)|Stigma]]: {{Unicode|Ϛ}}), early 50 ({{Unicode|ↆ}}, similar to down arrow {{Unicode|↓⫝⊥}}<ref name="PropN3218"/>), 50,000, and 100,000.  Note that the small reversed c, {{Unicode|ↄ}} is not intended to be used in roman numerals, but as [[lower case]] [[Claudian letter]] {{Unicode|Ↄ}},  

{| class="wikitable"
|+ Table of Roman numerals in Unicode
|-
! Code!!0!!1!!2!!3!!4!!5!!6!!7!!8!!9!!A!!B!!C!!D!!E!!F
|-
! Value<ref>For the first two rows</ref>!!1!!2!!3!!4!!5!!6!!7!!8!!9!!10!!11!!12!!50!!100!!500!!1,000
|-

! U+2160
|Ⅰ||Ⅱ||Ⅲ||Ⅳ||Ⅴ||Ⅵ||Ⅶ||Ⅷ||Ⅸ||Ⅹ||Ⅺ||Ⅻ||Ⅼ||Ⅽ||Ⅾ||Ⅿ
|-
! U+2170
|ⅰ||ⅱ||ⅲ||ⅳ||ⅴ||ⅵ||ⅶ||ⅷ||ⅸ||ⅹ||ⅺ||ⅻ||ⅼ||ⅽ||ⅾ||ⅿ
|-
! Value!!1000!!5000!!10,000!!–!!–!!6!!50!!50,000!!100,000!!colspan=7|
|-
! U+2180
|ↀ||ↁ||ↂ||Ↄ||ↄ||ↅ||ↆ||ↇ||ↈ||colspan=7|
|}

The characters in the range U+2160&ndash;217F are present only for [[Unicode compatibility characters|compatibility]] with other character set standards which provide these characters. For ordinary uses, the standard Latin letters are preferred. Displaying these characters requires a program that can handle Unicode and a [[typeface|font]] that contains appropriate glyphs for them.

== Games ==
After the [[Renaissance]], the Roman system could also be used to write [[chronogram]]s. It was common to put in the first page of a book some phrase, so that when adding the I, V, X, L, C, D, M present in the phrase, the reader would obtain a number, usually the year of publication. The phrase was often (but not always) in Latin, as chronograms can be rendered in any language that utilises the Roman alphabet.

== See also ==
* [[Kharoṣṭhī numerals]]
* [[Urnfield culture numerals]]

== References ==
{{reflist}}
* {{cite book | author=Menninger, Karl| title=Number Words and Number Symbols: A Cultural History of Numbers | publisher=[[Dover Publications]] | year=1992 | isbn=0-486-27096-3}}

== External links ==
{{Wiktionary|Appendix:Roman numerals|roman numeral}}
{{Commons category}}
* [http://www.moxlotus.alternatifs.eu/programmation-converter.html Conversion algorithm and demonstration program (with java source code)] for numbers up to 3,999
* [http://jeankorte.ca/jk-roman-numeral-converter.html Conversion program (with javascript source code)] for numbers up to 3,999,999
* [http://www.ubr.com/clocks/faq/iiii.html FAQ #1 Why do clocks with Roman numerals use "IIII" instead of "IV"?: ]
* [http://www.australiannumerals.com/ArabicNumeralstoRomanNumeralsNumbersConverter.html Minor history of the rules of Roman Numerals and an Arabic to Roman Numeral Converter]
* [http://netzreport.googlepages.com/online_converter_for_dec_roman.html Online Converter] for Decimal/Roman Numerals ([[JavaScript]], [[GPL]])
* [http://www.psinvention.com/zoetic/romanJava.htm Roman Numeral Conversion Exercises] ([[Java (programming language)|Java]])
* [http://niquette.com/puzzles/romannp.htm ''Romance in Numbers''] by Paul Niquette
* [http://codeguru.earthweb.com/print.php/c4569 Simple Roman Numeral Converter in C] ([[C (programming language)|C]])
* [http://www.utilitymill.com/utility/Decimal_to_Roman_Numerals Web Based Converter - Decimal to Roman Numerals]
* [[:File:Bescherelle - Grammaire nationale.djvu|French book with 841 chapters, numbered up to DCCCXLI]]

{{Latin alphabet}}
{{Ancient Rome topics}}

{{DEFAULTSORT:Roman Numerals}}
[[Category:Numerals]]
[[Category:Numeration]]
[[Category:Roman mathematics]]
[[Category:Latin alphabet]]

[[ar:أرقام رومانية]]
[[az:Rum rəqəmləri]]
[[zh-min-nan:Lô-má sò͘-jī]]
[[be:Рымская сістэма злічэння]]
[[be-x-old:Рымскія лічбы]]
[[bs:Rimski brojevi]]
[[br:Niveradur roman]]
[[bg:Римски цифри]]
[[ca:Numeració romana]]
[[cv:Рим шутлав йĕрки]]
[[cs:Římské číslice]]
[[da:Romertal]]
[[de:Römische Zahlen]]
[[et:Rooma numbrid]]
[[es:Numeración romana]]
[[eo:Romiaj ciferoj]]
[[eu:Zenbaketa erromatar]]
[[fa:عددنویسی رومی]]
[[fr:Numération romaine]]
[[ga:Uimhir Rómhánach]]
[[gl:Numeración romana]]
[[ko:로마 숫자]]
[[hr:Rimski brojevi]]
[[id:Angka Romawi]]
[[is:Rómverskir tölustafir]]
[[it:Sistema di numerazione romano]]
[[he:ספרות רומיות]]
[[kn:ರೋಮನ್ ಅಂಕಿಗಳು]]
[[sw:Namba za Kiroma]]
[[ku:Hejmarên romî]]
[[la:Numeri Romani]]
[[lv:Romiešu skaitļi]]
[[lt:Romėniški skaičiai]]
[[hu:Római szám]]
[[mk:Римски броеви]]
[[ms:Angka Rumi]]
[[nl:Romeinse cijfers]]
[[ja:ローマ数字]]
[[no:Romertall]]
[[nn:Romartal]]
[[nrm:Chiffes romaines]]
[[nds:Röömsche Tallen]]
[[pl:Rzymski system zapisywania liczb]]
[[pt:Numeração romana]]
[[ru:Римские цифры]]
[[sq:Numrat romakë]]
[[scn:Nùmmura rumani]]
[[simple:Roman numeral]]
[[sk:Rímske číslice]]
[[sl:Rimske številke]]
[[sr:Римски бројеви]]
[[fi:Roomalaiset numerot]]
[[sv:Romerska siffror]]
[[ta:ரோம எண்ணுருக்கள்]]
[[th:เลขโรมัน]]
[[tr:Roma rakamları]]
[[uk:Римська система цифр]]
[[vi:Số La Mã]]
[[yi:רוימישע צאל]]
[[zh:罗马数字]]