Roman numerals- numbers used by the ancient Romans in their non-positional number system.

Natural numbers are written by repeating these numbers. At the same time, if big number stands in front of the smaller one, then they add up (the principle of addition), but if the smaller one is in front of the larger one, then the smaller one is subtracted from the larger one (the principle of subtraction). The last rule applies only to avoid repeating the same number four times.

Roman numerals appeared around 500 BC among the Etruscans.

Numbers

To consolidate in memory letter designations numbers in descending order there is a mnemonic rule:

M s D arim WITH face-to-face L imons, X vatit V seven I X.

Respectively M, D, C, L, X, V, I

For correct recording large numbers Using Roman numerals, you must first write down the number of thousands, then hundreds, then tens, and finally units.

There is a "shortcut" for writing large numbers such as 1999. It is not recommended, but is sometimes used to simplify things. The difference is that to reduce a digit, any digit can be written to the left of it:

• 999. Thousand (M), subtract 1 (I), we get 999 (IM) instead of CMXCIX. Consequence: 1999 - MIM instead of MCMXCIX
• 95. One hundred (C), subtract 5 (V), get 95 (VC) instead of XCV
• 1950: Thousand (M), subtract 50 (L), get 950 (LM). Consequence: 1950 - MLM instead of MCML

It was only in the 19th century that the number “four” was written down as “IV”; before that, the number “IIII” was most often used. However, the entry “IV” can already be found in the documents of the Forme of Cury manuscript dating back to 1390. Watch dials have traditionally used "IIII" instead of "IV" in most cases, mainly for aesthetic reasons: this spelling provides visual symmetry with the "VIII" numerals on the opposite side, and an inverted "IV" is more difficult to read than "IIII".

Application of Roman numerals

In Russian, Roman numerals are used in the following cases:

• Century or millennium number: XIX century, II millennium BC. e.
• Serial number of the monarch: Charles V, Catherine II.
• The volume number in a multi-volume book (sometimes the numbers of parts of the book, sections or chapters).
• In some publications - the numbers of sheets with the preface to the book, so as not to correct the links within the main text when changing the preface.
• Antique watch dial markings.
• Others important events or list items, for example: Euclid's V postulate,II World War, XXII Congress of the CPSU, etc.

In other languages, the scope of application of Roman numerals may have specific features; for example, in Western countries, the year number is sometimes written in Roman numerals.

Roman numerals and Unicode

The Unicode standard defines characters to represent Roman numerals as part of Number forms(English) Number Forms), in the area of ​​characters with codes U+2160 to U+2188. For example, MCMLXXXVIII can be represented in the form ⅯⅭⅯⅬⅩⅩⅩⅧ . This range includes both lowercase and uppercase numerals from 1 (Ⅰ or I) to 12 (Ⅻ or XII), including combination glyphs for composite numbers, such as 8 (Ⅷ or VIII), mainly to provide compatibility with East Asian character sets in industry standards such as JIS X 0213, where these characters are defined. Combination glyphs are used to represent numbers that were previously composed of individual characters (for example, Ⅻ instead of its representation as Ⅹ and Ⅱ). In addition to this, glyphs exist for the archaic forms of writing the numbers 1000, 5000, 10,000, major reverse C (Ɔ), the later form of writing 6 (ↅ, similar to the Greek stigma: Ϛ), early form notations for the number 50 (ↆ, which looks like a downward-pointing arrow ↓⫝⊥), 50,000, and 100,000. It should be noted that the small reverse c, ↄ is not included in Roman numeral symbols, but is included in the Unicode standard as the uppercase Claudian letter Ↄ .

Roman numerals to Unicode

Code	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
Meaning	1	2	3	4	5	6	7	8	9	10	11	12	50	100	500	1 000
U+2160	Ⅰ 2160	Ⅱ 2161	Ⅲ 2162	Ⅳ 2163	Ⅴ 2164	Ⅵ 2165	Ⅶ 2166	Ⅷ 2167	Ⅸ 2168	Ⅹ 2169	Ⅺ 216A	Ⅻ 216B	Ⅼ 216C	Ⅽ 216D	Ⅾ 216E	Ⅿ 216F
U+2170	ⅰ 2170	ⅱ 2171	ⅲ 2172	ⅳ 2173	ⅴ 2174	ⅵ 2175	ⅶ 2176	ⅷ 2177	ⅸ 2178	ⅹ 2179	ⅺ 217A	ⅻ 217B	ⅼ 217C	ⅽ 217D	ⅾ 217E	ⅿ 217F
Meaning	1 000		5 000		10 000		-	-	6		50		50 000		100 000
U+2160! U+2180	ↀ 2180		ↁ 2181		ↂ 2182		Ↄ	ↄ	ↄ		ↄ		ↄ		ↄ

Characters in the range U+2160-217F are present only for compatibility with other standards that define these characters. Common letters are used in everyday life Latin alphabet. Displaying such symbols requires software, which supports the Unicode standard, and a font containing the glyphs corresponding to these characters.

The Roman numbering system using letters was widespread in Ancient Rome and Europe for two thousand years. Only in the late Middle Ages was it replaced by a more convenient decimal system of numbers, borrowed from the Arabs (1,2,3,4,5...).

But, until now, Roman numerals indicate dates on monuments, time on clocks and (in the Anglo-American typographic tradition) pages of book prefaces, clothing sizes, chapters of monographs and textbooks. In addition, in Russian it is customary to use Roman numerals to denote ordinal numbers. The Roman numeral system is currently used to designate centuries (XV century, etc.), AD. e. (MCMLXXVII, etc.) and months when indicating dates (for example, 1. V. 1975), in historical monuments of law as article numbers (Karolina, etc.)

To designate numbers, 7 letters of the Latin alphabet were used (the first letter of the words is five, ten, fifty, one hundred, five hundred, thousand):

I=1, V=5, X=10, L=50, C=100, D=500, M=1000

C (100) is the first letter of the Latin word centum (one hundred)

and M - (1000) - the first letter of the word mille (thousand).

As for the sign D (500), it was half of the sign Ф (1000)

The V sign (5) is the upper half of the X sign (10)

Intermediate numbers were formed by adding several letters to the right or left. Thousands and hundreds are written first, then tens and ones. So the number 24 is written as XXIV

Natural numbers are written by repeating these numbers.

Moreover, if a larger number is in front of a smaller one, then they are added (the principle of addition), but if a smaller number is in front of a larger one, then the smaller one is subtracted from the larger one (the principle of subtraction).

In other words, if a sign denoting a smaller number is to the right of a sign denoting a larger number, then the smaller is added to the larger; if on the left, then subtract: VI - 6, i.e. 5+1 IV - 4, i.e. 5-1 LX - 60, i.e. 50+10 XL - 40, i.e. 50-10 CX - 110, i.e. 100+10 XC - 90, i.e. 100-10 MDCCCXII - 1812, i.e. 1000+500+100+100+100+10+1+1

The last rule applies only to avoid repeating the same number four times. To avoid repetition 4 times, the number 3999 is written as MMMIM.

Different designations for the same number are possible. Thus, the number 80 can be represented as LXXX (50+10+10+10) and as XXC(100-20).

For example, I, X, C are placed respectively before X, C, M to indicate 9, 90, 900 or before V, L, D to indicate 4, 40, 400.

For example, VI = 5+1 = 6, IV = 5 - 1 = 4 (instead of IIII).

XIX = 10 + 10 - 1 = 19 (instead of XVIIII),

XL = 50 - 10 =40 (instead of XXXX),

XXXIII = 10 + 10 + 10 + 1 + 1 + 1 = 33, etc.

Roman numerals

MCMLXXXIV

Note:

Basic Roman numerals: I (1) - unus (unus) II (2) - duo (duo) III (3) - tres (tres) IV (4) - quattuor (quattuor) V (5) - quinque (quinque) VI (6) - sex (sex) VII (7) - septem (septem) VIII (8) - octo (octo) IX (9) - novem (novem) X (10) - decem (decem), etc. XX (20) - viginti (viginti) XXI (21) - unus et viginti or viginti unus XXII (22) - duo et viginti or viginti duo, etc. XXVIII (28) - duodetriginta XXIX (29) - undetriginta XXX (30) - triginta XL (40) - quadraginta L (50) - quinquaginta LX (60) - sexaginta LXX (70) - septuaginta LXXX (80) - octoginta XC (90) - nonaginta C (100) - centum CC (200) - ducenti CCC (300) - trecenti (trecenti) CD (400) - quadrigenti (quadrigenti) D (500) - quingenti (quingenti) DC (600) - sexcenti (sexcenti) DCC (700) - septigenti (septigenti) DCCC(800) - octingenti (octigenti) CM (DCCCC) (900) - nongenti (nongenti) M (1000) - mille (mille) MM (2000) - duo milia (duo milia) V (5000) - quinque milia (quinque milia) X (10000) - decem milia (decem milia) XX (20000) - viginti milia (viginti milia) C (1000000) - centum milia (centum milia) XI (1000000) - decies centena milia (decies centena milia)"

Today in Russia, Roman numerals are needed, first of all, to record the number of the century or millennium. It is convenient to place Roman numerals next to Arabic ones - if you write the century in Roman numerals, and then the year in Arabic, then your eyes will not be dazzled by the abundance of identical signs. Roman numerals have a certain connotation of archaism. They are also traditionally used to indicate the serial number of the monarch (Peter I), the volume number of a multi-volume publication, and sometimes the chapter of a book. Roman numerals are also used in antique watch dials. Important numbers, such as the year of the Olympiad or number scientific law, can also be recorded using Roman numerals: World War II, Euclid’s V postulate.

IN different countries Roman numerals are used slightly differently: in the USSR it was customary to indicate the month of the year using them (1.XI.65). In the West, the year number is often written in Roman numerals in the credits of films or on the facades of buildings.

In parts of Europe, especially in Lithuania, you can often find the days of the week designated in Roman numerals (I – Monday, and so on). In Holland, Roman numerals are sometimes used to denote floors. And in Italy they mark 100-meter sections of the path, marking, at the same time, Arabic numerals every kilometer.

In Russia, when writing by hand, it is customary to emphasize the Roman numerals below and above at the same time. However, often in other countries, the underscore meant increasing the case of the number by 1000 times (or 10,000 times with a double underscore).

There is a common misconception that modern Western clothing sizes have some connection with Roman numerals. In fact, the designations are XXL, S, M, L, etc. have no connection with them: these are abbreviations English words eXtra (very), Small (small), Large (large).

Today in Russia, Roman numerals are needed, first of all, to record the number of the century or millennium. It is convenient to place Roman numerals next to Arabic ones - if you write the century in Roman numerals, and then the year in Arabic, then your eyes will not be dazzled by the abundance of identical signs. Roman numerals have a certain connotation of archaism. They are also traditionally used to indicate the serial number of the monarch (Peter I), the volume number of a multi-volume publication, and sometimes the chapter of a book. Roman numerals are also used in antique watch dials. Important numbers, such as the year of the Olympiad or the number of a scientific law, can also be recorded using Roman numerals: World War II, Euclid's V postulate.

In different countries, Roman numerals are used slightly differently: in the USSR it was customary to indicate the month of the year using them (1.XI.65). In the West, the year number is often written in Roman numerals in the credits of films or on the facades of buildings.

In parts of Europe, especially in Lithuania, you can often find the days of the week designated in Roman numerals (I – Monday, and so on). In Holland, Roman numerals are sometimes used to denote floors. And in Italy they mark 100-meter sections of the route, marking, at the same time, every kilometer with Arabic numerals.

In Russia, when writing by hand, it is customary to emphasize the Roman numerals below and above at the same time. However, often in other countries, the underscore meant increasing the case of the number by 1000 times (or 10,000 times with a double underscore).

There is a common misconception that modern Western clothing sizes have some connection with Roman numerals. In fact, the designations are XXL, S, M, L, etc. have no connection with them: these are abbreviations of the English words eXtra (very), Small (small), Large (large).

21st	XXI
20th	XX
19th	XIX
18th	XVIII
17th	XVII
16th	XVI
15th	XV
14th	XIV
13th	XIII
12th	XII
11th	XI
10th	X
9th	IX
8th	VIII
7th	VII
6th	VI
5th	V
4th	IV
3rd	III
2nd	II
1st	I

Roman numerals, invented more than 2,500 years ago, were used by Europeans for two millennia before being replaced by Arabic numerals. This happened because Roman numerals are quite difficult to write, and any arithmetic operations in the Roman system are much more difficult to perform than in the Arabic number system. Despite the fact that the Roman system is not often used today, this does not mean that it has become irrelevant. In most cases, centuries are denoted by Roman numerals, but years or exact dates It is customary to write in Arabic numerals.

Roman numerals are also used when writing serial numbers monarchs, encyclopedic volumes, valency of various chemical elements. On the dials wristwatch numerals from the Roman numeral system are also often used.

Roman numerals are specific characters used to write decimal places and their halves. For this purpose, only seven capital letters of the Latin alphabet are used. The number 1 corresponds to the Roman numeral I, 5 – V, 10 – X, 50 – L, 100 – C, 500 – D, 1000 – M. When designating natural numbers these numbers are repeated. So 2 can be written using two times I, that is, 2 – II, 3 - three letters I, that is, 3 – III. If a smaller digit comes before a larger one, then the principle of subtraction is used (the smaller digit is subtracted from the larger one). So, the number 4 is depicted as IV (that is, 5-1).

In the case when a larger number comes in front of a smaller one, they are added, for example, 6 is written in the Roman system as VI (that is, 5+1).

If you are used to writing numbers in Arabic numerals, then some difficulties may arise when you need to write centuries in Roman numerals, a number or a date. You can convert any number from the Arabic system to the Roman number system and vice versa very easily and very quickly using the convenient converter on our website.

On your computer keyboard, just go to English language to easily write any number in Roman numerals.

Apparently, the ancient Romans preferred straight lines, which is why all their numbers are straight and strict. However, Roman numerals are nothing more than a simplified image of the fingers of a human hand. The numbers one to four resemble outstretched fingers, the number five can be compared to an open palm, where thumb protruded. And the number ten resembles two crossed hands. IN European countries When counting, it is customary to straighten your fingers, but in Russia, on the contrary, bend them.