Roman numerals or Roman Numbers are a numbering system that originated in ancient Rome. This numbering system uses Latin letters to symbolize numerical numbers. The principal or basic symbols of Roman numbers include:
| I | V | X | L | C | D | M |
| 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
| IV | IX | XL | XC | CD | CM |
| 4 | 9 | 40 | 90 | 400 | 900 |
| V | X | L | C | D | M |
| 5.000 | 10.000 | 50.000 | 100.000 | 500.000 | 1.000.000 |
| IV | IX | XL | XC | CD | CM |
| 4.000 | 9.000 | 40.000 | 90.000 | 400.000 | 900.000 |
- Roman numerals use a system of repetition, addition, subtraction and mixed combination.
- Read the number from left to right.
• Roman numbers are written side by side.
• The maximum number of times a Roman numeral can be repeated is three.
• The main Roman numbers that can be repeated are I, X, C, and M.
• V, L, and D cannot be repeated.
Examples:
I = 1
II = 2
III = 3
X = 10
XX = 20
XXX = 30
C = 100
CC = 200
CCC = 300
M = 1000
MM = 2000
MMM = 3000
The addition rule applies when the base Roman numeral is followed (on its right) by an equal or smaller.
Examples:
III = 1 + 1 + 1 = 3
VII = 5 + 1 + 1 = 7
XIII = 10 + 1 + 1 + 1 = 13
XV = 10 + 5 = 15
LVI = 50 + 5 + 1 = 56
LXV = 50 + 10 + 5 = 65
MD = 1000 + 500 = 1500
CX = 100 + 10 = 110
CLXXVIII = 100 + 50 + 10 + 10 + 5 + 1 + 1 + 1 = 178
The Subtraction rule applies when the base Roman numeral is followed (on its right) by a larger number. The principle of subtraction is as follows.
• Each subtraction can only be performed once on the same number.
• V, L, and D CANNOT be used to subtract.
• I can only be used to subtract V and X.
• X can only be used to subtract L and C.
• C can only be used to subtract D and M
Examples:
IV = (-1) + 5 = 4
IX = (-1) + 10 = 9
XL = (-10) + 50 = 40
XC = (-10) + 100 = 90
CD = (-100) + 500 = 400
CM = (-100) + 1000 = 900
Subtractive Rule of Roman Numerals
| Write ✓ | Instead of ✘ | Value of № |
|---|---|---|
| IV | IIII | 4 |
| IX | VIIII | 9 |
| XL | XXXX | 40 |
| XC | LXXXX | 90 |
| CD | CCCC | 400 |
| CM | DCCCC | 900 |
Combination of the Three Rules of Roman Numbers.
Examples:
XLVIII = XL + VIII = 40 + 8 = 48
XLIX = XL + IX = 40 + 9 = 49
XCIX = XC + IX = 90 + 9 = 99
CCCXCVIII = CCC + XC + VIII = 300 + 90 + 8 = 398
MCMXCIX = M + CM + XC + IX = 1000 + 900 + 90 + 9 = 1999
CDL = CD + L = 400 + 50 = 450
MMXLVIII = M + M + XL + VIII = 2048
How to Convert to Roman Numerals?
An easy way to convert numbers is to write the numbers from largest to smallest, from left to right.
- 1000 = M
- 100 = C
- 10 = X
- 1 = I
So 1111 = MCXI
| Thousands | |
|---|---|
| 1000 | M |
| 2000 | MM |
| 3000 | MMM |
| 4000 | I̅V̅ |
| 5000 | V̅ |
| 6000 | V̅M |
| 7000 | V̅MM |
| 8000 | V̅MMM |
| 9000 | I̅X̅ |
| Hundreds | |
|---|---|
| 100 | C |
| 200 | CC |
| 300 | CCC |
| 400 | CD |
| 500 | D |
| 600 | DC |
| 700 | DCC |
| 800 | DCCC |
| 900 | CM |
| Tens | |
|---|---|
| 10 | X |
| 20 | XX |
| 30 | XXX |
| 40 | XL |
| 50 | L |
| 60 | LX |
| 70 | LXX |
| 80 | LXXX |
| 90 | XC |
| Units | |
|---|---|
| 1 | I |
| 2 | II |
| 3 | III |
| 4 | IV |
| 5 | V |
| 6 | VI |
| 7 | VII |
| 8 | VIII |
| 9 | IX |
1. Convert 1992 to Roman numerals.
Solution:
Break 1992 into 1000, 900, 90 and 2.
• 1000 = M
• 900 = CM
• 90 = XC
• 2 = II
so, 1992 = M + CM + XC + II = MCMXCII
2. How to write roman numerals 35?
Solution:
Break 35 into tens and units
35 = 30 + 5
35 = XXX + V
35 = XXXV
3. What is MXXIX in roman numerals?
Solution:
M = 1000
XX = 20
IX = 9
So, MXXIX = 1029
Roman Numerals Chart
To make it easier to write Roman numerals, below we provide a complete chart from 1 to 1,000,000.
Download Printable Numerals Chart (PDF)
Why do we need to learn Roman numerals?
Many students don’t understand the Roman numeral system. The Roman number system dates back to three centuries ago or about 300 years. The system uses letters of the alphabet to symbolize numerical numbers.
In elementary school, Roman numbers are not important, but on the contrary, Roman numbers taught in elementary school are important. As we know in everyday life, Roman numerals are often found.
Roman numerals are often found in some writing, such as writing chapter numbers in books, writing class levels, and numbering street addresses. This shows that are important to learn and master.
Many students dislike math because they find it difficult, especially Roman numerals. Most students are almost the same, namely the difficulty in distinguishing the symbols of Roman numbers, because they easily forget the symbols of Roman numbers and tend to be bored with this material for various reasons, for example students say the method taught is like that, lazy to think, and also confused in reading numerals that have been combined.
History
The Roman numeration system has existed since 260 years BC. The system develops continuously and undergoes development. In the Roman numeration system, some basic symbols are I, V, X, L, C, D, M which represent the numbers one, five, ten, fifty, one hundred, five hundred, and one thousand respectively. Other numbers are written using these basic symbols with certain rules.
Initially, the calculation system was adapted from the Etruscan calculation system. Likewise, the numbers are very similar to the Etruscan numbers (symbolized by letters and pictures). But since Etruscan numbers are difficult to write or read, finally in medieval times Roman numerals were simplified.
Roman numerals are written with symbols of available numbers then added or subtracted. For larger numbers (≥ 5000), a line was placed above the symbol indicating multiplication by 1000.
Roman numerals are very commonly used today, including in clocks, book chapters, numbering movie sequels, numbering sports event series such as the Olympics, numbering street addresses and others.