Roman Numerals
The numeric system represented by Roman numerals originated in ancient Rome (753 BC–476 AD) and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages (generally comprising the 14th and 15th centuries (c. 1301–1500)). Numbers in this system are represented by combinations of letters from the Latin alphabet. Roman numerals, as used today, are based on seven symbols:
| Symbol | I | V | X | L | C | D | M |
| Value | [latex]1[/latex] | [latex]5[/latex] | [latex]10[/latex] | [latex]50[/latex] | [latex]100[/latex] | [latex]500[/latex] | [latex]1,000[/latex] |
The use of Roman numerals continued long after the decline of the Roman Empire. From the 14th century on, Roman numerals began to be replaced in most contexts by the more convenient Hindu-Arabic numerals; however, this process was gradual, and the use of Roman numerals persists in some minor applications to this day.
The numbers [latex]1[/latex] to [latex]10[/latex] are usually expressed in Roman numerals as follows:
Numbers are formed by combining symbols and adding the values, so II is two (two ones) and XIII is thirteen (a ten and three ones). Because each numeral has a fixed value rather than representing multiples of ten, one hundred and so on, according to position, there is no need for “place keeping” zeros, as in numbers like [latex]207[/latex] or [latex]1066[/latex]; those numbers are written as CCVII (two hundreds, a five and two ones) and MLXVI (a thousand, a fifty, a ten, a five and a one).
Symbols are placed from left to right in order of value, starting with the largest. However, in a few specific cases, to avoid four characters being repeated in succession (such as IIII or XXXX), subtractive notation is used: as in this table:
| Roman Numeral | IV | IX | XL | XC | CD | CM |
| Number | [latex]4[/latex] | [latex]9[/latex] | [latex]40[/latex] | [latex]90[/latex] | [latex]400[/latex] | [latex]900[/latex] |
In summary:
- I placed before V or X indicates one less, so four is IV (one less than five) and nine is IX (one less than ten)
- X placed before L or C indicates ten less, so forty is XL (ten less than fifty) and ninety is XC (ten less than a hundred)
- C placed before D or M indicates a hundred less, so four hundred is CD (a hundred less than five hundred) and nine hundred is CM (a hundred less than a thousand)
roman numerals
Roman numerals, formed from seven Latin letters, represent numbers as combinations of symbols I, V, X, L, C, D, and M. The placement of these symbols relative to each other determines their value, adding or subtracting to yield the final number.
How to: Read Roman Numerals
- Identify the Symbols: Recognize the seven basic symbols: I ([latex]1[/latex]), V ([latex]5[/latex]), X ([latex]10[/latex]), L ([latex]50[/latex]), C ([latex]100[/latex]), D ([latex]500[/latex]), and M ([latex]1000[/latex]).
- Understand the Order: A smaller numeral before a larger one means subtraction (e.g., IV equals [latex]4[/latex]). A smaller numeral after a larger one means addition (e.g., VI equals [latex]6[/latex]).
- Combine Values: Begin from the left, working your way to the right. Add up the symbols’ values, subtracting or adding as you go. For example, in the numeral XC ([latex]90[/latex]), you subtract X ([latex]10[/latex]) from C ([latex]100[/latex]).
- Calculate the Number: After processing each symbol in sequence, sum your calculated values to find the final number the Roman numerals represent. Consider any sequences of subtraction as single operations within the larger sum. For instance, MCMIV ([latex]1904[/latex]) is calculated as M ([latex]1000[/latex]) plus CM ([latex]900[/latex]) plus IV ([latex]4[/latex]).
Modern Use
By the 11th century, Hindu–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:
- Names of monarchs and popes, e.g. Elizabeth II of the United Kingdom, Pope Benedict XVI. These are referred to as regnal numbers; e.g. II is pronounced “the second”. This tradition began in Europe sporadically in the Middle Ages, gaining widespread use in England only 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 and Louis XIV of France) seem to have preferred the use of IIII instead of IV on their coinage (see image above).
- Generational suffixes, particularly in the US, for people sharing the same name across generations, for example William Howard Taft IV.
- In the French Republican Calendar, initiated during the French Revolution, years were numbered by Roman numerals – from the year I (1792) when this calendar was introduced to the year XIV (1805) when it was abandoned.
- Hour marks on timepieces. In this context, [latex]4[/latex] is usually written IIII.
- The year of construction on building faces and cornerstones.
- Page numbering of prefaces and introductions of books, and sometimes of annexes, too.
- Book volume and chapter numbers, as well as the several acts within a play (e.g. Act iii, Scene 2).
- Sequels of some movies, video games, and other works (as in Rocky II).
- Outlines that use numbers to show hierarchical relationships.
- Occurrences of a recurring grand event, for instance:
- The Summer and Winter Olympic Games (e.g. the XXI Olympic Winter Games; the Games of the XXX Olympiad)
- The Super Bowl, the annual championship game of the National Football League (e.g. Super Bowl XXXVII; Super Bowl 50 is a one-time exception)
- WrestleMania, the annual professional wrestling event for the WWE (e.g. WrestleMania XXX). This usage has also been inconsistent.