**What are Roman numerals?**

It is known as **Roman numerals** to the numbering system used during the Roman Empire, between the years 27 before our era and 476 of the common era.

Due to the enormous cultural prestige that the Roman Empire has preserved many centuries after its collapse, both its language (Latin) and its numbering system are still used in some specific cases.

The Roman numbering system, however, was not invented by the Romans themselves, but originated among the Etruscans. This people arrived in the central part of the Italian peninsula from Turkey and central Europe long before the founding of Rome, and by that time they had already developed a sophisticated culture.

**What are Roman numerals still used for today?**

**For** **write the number of centuries**

Examples: «The eighteenth century is known as the Age of Enlightenment»; «Columbus first arrived in America at the end of the 15th century.»

**To differentiate between kings and popes**

Examples: In the history of Spain there have been six monarchs with the name of Felipe; it differentiates between them using Roman numerals: Felipe II, Felipe V, etc.

The Catholic Church has been headed by 23 Popes named John: John IV, John XVI, John XXIII, etc.

**To number chapters, volumes or parts**

Examples: Gospel of Luke, chapter II; Hispanic Encyclopedia, volume XI; *Star Wars*: episode IX.

**To list periodic events or celebrations**

Examples: XXX Guadalajara International Book Fair; XXII FIFA Soccer World Cup Qatar 2022.

**Why don’t we use Roman numerals to do arithmetic anymore?**

As you will have already observed, Roman numerals are useful for writing specific figures, even somewhat high ones, such as MMXXII, which corresponds to the current year, 2022.

But it is another matter when it comes to arithmetic operations. Since the years of the Roman Empire, both mathematicians and state administration officials understood that the system was very inefficient and complicated when it came to adding, dividing or multiplying.

However, it would be centuries before, with the fall of the Roman Empire, the Europeans knew a more efficient numbering system. This came through the Arab countries, which is why it was called Arabic, although it was actually invented in India in the fifth century AD.

Arabic numerals are the ones we normally use, from 1 to 9 and 0. However, the decimal system we use to build larger figures is an original invention of Arab culture.

**How to use roman numerals**

The Roman numeral system is based on seven capital letters, each of which corresponds to a specific number value:

**Yo**: 1

**V**: 5

**X**:10

**L**: fifty

**C.**:100

**D.**:500

**m**:1000

To write a number, these letters are combined horizontally and added according to the following rules:

**1. It is written from left to right and from major to minor**

To represent the number 11, I take the letter of numerical value 10 (**X**) and add the letter that equals 1 (**Yo**), which results in **eleventh**.

If I want to indicate the number 30, it is enough to repeat the letter with the numerical value 10 three times, that is, **xxx**.

**2. If to the left of a certain letter another of lesser value appears, it indicates a subtraction**

As we have seen, **eleventh** is equivalent to 11; but if the letters are reversed (**IX**), the number obtained is 9, since **Yo **1 is left to **X**whose value is 10.

The same happens in **fourteenth**. This is equivalent to 10 + 5 – 1, that is, 14.

**3. In the case of subtraction, the following three conditions must be respected**

The letter **Yo** can only subtract letters **V** and **X**. Examples: **IV.** (4), **XIX **(19).

The letter **X** can only subtract letters **L** and **C.**. Examples: **XL** (40), **CXC** (190).

The letter **C.** can only subtract letters **D.** and **m**. Examples: **CD** (400), **LCM** (1900)

**4. The letters V, L and D (5, 50 and 500, respectively) cannot be placed in a subtraction position, but always add**

If we wish to represent the number 45, it would be incorrect to place VL, since **V** cannot exercise the subtraction function. must be written **XLV**which is equivalent to 55 – 10.

Likewise, it would be wrong to write the number 110 like this: CLC. The correct is **C-X**.

**5.** **A letter cannot be repeated more than three consecutive times**

**II **equals 3; but to represent the number 4 I can no longer add another **Yo**but I must subtract: **IV.**.

The number 300 can be represented with three **C.**:** CCC**; but to indicate 400, I will still need to do a subtraction: **CD**500 – 100.

**Other examples of high figures in Roman numerals**

We already know that the letter **m** denotes the numerical value 1000, and that we can repeat it up to three times, reaching the figure of 3000. But how do we do it if we want to represent the number 4000 or higher?

In the Roman system, thousands greater than three thousand are indicated by a bar at the top. For example, to denote the number 4000 we write the letters that correspond to the number four (**IV.**) and add a bar at the top: **I̅V̅**. And the same with thousands of others: **V̅****V̅I̅I̅I̅**, **X̅**, etc. Look at the examples:

5981: **V̅CMLXXXI**

3465: **MMMCDLXV**

8871: **V̅I̅I̅I̅DCCCLXXI**

993: **CMXCIII**

22423: **X̅X̅MMCDXXIII**

10012: **X̅XII**

4755:** I̅V̅DCCLV**

56491: **L̅V̅I̅CDXCI**

882: **DCCCLXXXII**

**Roman numerals from 1 to 100, 500 and 1000**

1:I

2:II

3:III

4:IV

5:V

6:VI

7:VII

8:VIII

9:IX

10:X

11:XI

12:XII

13:XIII

14:XIV

15: fifteenth

16:16th

17:17th

18:18th

19:19

20:XX

21:XXI

22:XXII

23:XXIII

24:XXIV

25:XXV

26:XXVI

27:XXVII

28:XXVIII

29:XXIX

30:XXX

31:XXXI

32:XXXII

33:XXXIII

34:XXXIV

35:XXXV

36:XXXVI

37:XXXVII

38:XXXVIII

39:XXXIX

40:XL

41:XLI

42:XLII

43:XLIII

44:XLIV

45:XLV

46:XLVI

47:XLVII

48:XLVIII

49:XLIX

50:L

51:LI

52: LII

53: LIII

54: LIV

55: FV

56: LVI

57:LVII

58:LVIII

59: LIX

60:LX

61: LXII

62:62

63: LXIII

64:64

65:65

66: LXVI

67: LXVII

68: LXVIII

69:69

70:lxx

71: LXXI

72:LXXII

73: LXXIII

74: LXXIV

75: LXXXV

76: LXXVI

77: LXXVII

78: LXXVIII

79:LXXIX

80:LXXX

81: LXXXI

82: LXXXII

83: LXXXIII

84: LXXXIV

85: LXXXV

86: LXXXVI

87: LXXXVII

88: LXXXVIII

89: LXXXIX

90:X-C

91:XCI

92:XCII

93: XCIII

94: XCIV

95:XCV

96:XCVI

97:XCVII

98:XCVIII

99:XCIX

100:C

500 😀

1000:M