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Roman Numerals

Tool to convert from/in Roman numerals (I, V, X, L, C, D et M) allowing to write integer numbers and used in Antique Rome and make conversions.

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Roman Numerals -

Tag(s) : Numeral System, History

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# Roman Numerals

## Roman Numeral Writer

### What are Roman Numerals? (Definition)

Roman numerals are the name given to the numeral system used in ancient Roman times (especially in the time of Caesar), read from left to right it uses 7 letters whose values are added or subtracted according to their position.

### What are the letters to write in Roman Numerals?

Roman numeration uses 7 letters corresponding to 7 numbers. Roman digits chart from 1 to 1000:

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

Beyond several thousands, there are no letters to represent these numbers.

However, some archaic scripts (more rare) used 4 other symbols

 Ɔ 500 ↀ 1000 ↁ 5000 ↂ 10000

### How to read/write with Roman numerals?

Roman numeral system uses two rules:

— (1) Any letter $L_2$ placed to the right of another letter $L_1$ are added if $L_2 \leq L_1$

Example: VI = 5 + 1 = 6
XX = 10 + 10 = 20

— (2) Any letter of unit $L_1 = \rm{I}$ placed immediately to the left of another letter $L_2 \neq \rm{I}$ is subtracted.

Example: IV = 5 - 1 = 4
IX = 10 - 1 = 9
IL = 50 - 1 = 49
IC = 100 - 1 = 99
ID = 500 - 1 = 499

Rule (2) is sometimes extended to: Any letter $L_1$ placed immediately to the left of another letter $L_2 > L_1$ is subtracted.

Example: XC = 100 - 10 = 90

In theory therefore, any symbol (letter) is repeated a maximum of 3 times consecutively.

Example:

1970 in roman numerals 1971 in roman numerals MCMLXX MCMLXXI MCMLXXII MCMLXXIII MCMLXXIV MCMLXXV MCMLXXVI MCMLXXVII MCMLXXVIII MCMLXXIX MCMLXXX MCMLXXXI MCMLXXXII MCMLXXXIII MCMLXXXIV MCMLXXXV MCMLXXXVI MCMLXXXVII MCMLXXXVIII MCMLXXXIX MCMXC MCMXCI MCMXCII MCMXCIII MCMXCIV MCMXCV MCMXCVI MCMXCVII MCMXCVIII MCMXCIX MM MMI MMII MMIII MMIV MMV MMVI MMVII MMVIII MMIX MMX MMXI MMXII MMXIII MMXIV MMXV MMXVI MMXVII MMXVIII MMXIX MMXX MMXXI MMXXII MMXXIII MMXXIV MMXXV

### How does the converter from/to Roman numerals work?

The program automatically detects whether the number is in Arabic or Roman numerals and makes the conversion/translation.

Roman numeration does not permit writing large numbers, beyond 9999 the program will display the number of thousands separately. This writing is not standardized but remains comprehensible.

The program is very permissive and allows badly formed Roman numbers not complying with the rule (2).

Example: IVX is translated as 6

### How to write zero (0) in Roman numerals?

Romans did not use the zero, for them it was not a digit but a state of emptiness, so they did not write it (the absence of a number indicates zero).

dCode writes either ??, or 0.

### How to write four (4) in Roman numerals?

Four is written IV, however, this software indicates that IIII = 4, unusual, IIII is a variant of IV which is tolerated. It can be found today (typically in watches, or clocks).

### How to write a date with roman numerals?

There is no specific way to write a date (or a birthdate), except to write the number of the day, the month and the year separately.

Example: 12 / 06 / 2008 = XII / VI / MMVIII

dCode has a tool to write a date in latin.

In some European countries, the centuries are sometimes written in Roman numerals.

### What is the biggest number in roman numerals?

Numbers above 10000 were not thinkable, without any calculation tool, they were useless. If you wish to write a value of hundreds of thousands, one can imagine writing hundreds of M at the beginning of the number.

Example: 9999 = MMMMMMMMMCMXCIX (a bit ridiculous)

### How to write negative numbers in roman numerals?

The negative writing is not recognized, it probably did not exist. The notion of positive or negative numbers is related to the concept of zero (which was not known to the Romans).

However, today, adding a - can help to be understood.

Example: -XXV = -25

### How to write a decimal number in roman numerals?

Using decimal numbers is very few documented in history books, however, it is probable that they used fractions, including a duodecimal currency system (base 12) which allowed sharing by 2, 3, 4, 6 and 12 without decimal places.

### When were Roman Numerals invented?

Roman numerals were born with Antique Rome, so starting at the 7th century BC. For example, they were used with Latin.

### How to write Roman Numerals with Unicode?

Roman numerals have been added to the Unicode standard, they encode by a single character each number from 1 to 12 (used in clocks and watches) and 8 other numbers meaning:

Unicode characterValueUnicode characterValueUnicode characterValue
123
456
789
101112
50100Ɔ500
50010001000
500010000

### Can there be more than 4 identical consecutive letters?

Roman numerals can be written with 4 identical letters in a row, but this is rare or incorrect.

Example: 4000 can be written MMMM or the watchmaker's four is written IIII

### When to use Roman Numerals?

Roman numerals are learned at school in primary school but are rarely used except in mathematics or history. The uses today are limited to clocks, dates, but also on tattoos, many tattoos use Roman numerals.

## Source code

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Cite as source (bibliography):
Roman Numerals on dCode.fr [online website], retrieved on 2024-06-14, https://www.dcode.fr/roman-numerals

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