## Roman Numbers

### The numeric system represented by Roman numerals originated in ancient Rome and remained the most common way of using numbers throughout Europe until the Late Middle Ages.

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                    1             5             10           50           100        500        1,000

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.

Image source: https://en.wikipedia.org/wiki/Roman_numerals

Info source: https://en.wikipedia.org/wiki/Roman_numerals

### How to read Roman numerals

Roman numbers are an additive (and subtractive) system in which letters are used to denote certain “base” numbers, and arbitrary numbers are then denoted using combinations of symbols:

he original pattern for Roman numerals used the symbols I, V. and X (1, 5, and 10) as simple tally marks. Each marker for 1 (I) added a unit value up to 5 (V), and was then added to (V) to make the numbers from 6 to 9:

I, II, III, IIII, V, VI, VII, VIII, VIIII, X.

The numerals for 4 (IIII) and 9 (VIIII) proved problematic (among other things, they are easily confused with III and VIII), and are generally replaced with IV (one less than 5) and IX (one less than 10). This feature of Roman numerals is called subtractive notation.

The system being basically decimal, tens and hundreds follow the same pattern:

Thus 10 to 100 (counting in tens, with X taking the place of I, L taking the place of V and C taking the place of X):

X, XX, XXX, XL, L, LX, LXX, LXXX, XC, C.

Note that 40 (XL) and 90 (XC) follow the same subtractive pattern as 4 and 9.

Info source: http://mathworld.wolfram.com/RomanNumerals.html

### Why have they been used for a long time?

The direct influence of Rome for such a long period, the superiority of its numeral system over any other simple one that had been known in Europe before about the 10th century, and the compelling force of tradition explain the strong position that the system maintained for nearly 2,000 years in commerce, in scientific and theological literature, and in belles lettres. It had the great advantage that, for the mass of users, memorizing the values of only four letters was necessary V, X, L, and C, and it was correspondingly easier to add numbers, the most basic arithmetic operation.

As in all such matters, the origin of these numerals is obscure, although the changes in their forms since the 3rd century bce are well known. The theory of German historian Theodor Mommsen (1850) had wide acceptance. He argued that the V for five represented the open hand. Two of these gave the X for 10, and the L, C, and M were modifications of Greek letters. However, study of inscriptions left by the Etruscans, who ruled Italy before the Romans, show that the Romans adopted the Etruscan numerical system beginning in the 5th century bce but with the distinct difference that the Etruscans read their numbers from right to left while the Romans read theirs from left to right. L and D for 50 and 500, respectively, emerged in the Late Roman Republic, and M did not come to mean 1,000 until the Middle Ages.

Info source: https://www.britannica.com/science/numeral

### Are they still being used today?

Some uses that are rare or never seen in English speaking countries are relatively common in continental Europe. For instance: Capital or small capital Roman numerals are widely used in Romance languages to denote centuries, e.g. the French xviiie siècle and the Spanish siglo XVIII mean “18th century”

Mixed Roman and Hindu-Arabic numerals are sometimes used in numeric representations of dates (especially in formal letters and official documents, but also on tombstones). The month is written in Roman numerals, while the day is in Hindu-Arabic numerals: “14.VI.1789” and “VI.14.1789” both refer unambiguously to 14 June 1789.

In Italy, where roads outside built-up areas have kilometre signs, major roads and motorways also mark 100-metre subdivisionals, using Roman numerals from I to IX for the smaller intervals. The sign “IX | 17” thus marks kilometre 17.9.

Image source: https://en.wikipedia.org/wiki/Roman_numerals

Info source: https://en.wikipedia.org/wiki/Roman_numerals