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
The correct Roman numerals 4, 9, 40, 90, 400 and 900 are as shown in the table below following the subtraction rules.
IV IX XL XC CD CM
4 9 40 90 400 900
For larger numbers (≥5,000), an overline is placed above the symbol, is called a vinculum. Which means that the Roman numeral is multiplied by 1000.
V X L C D M
5.000 10.000 50.000 100.000 500.000 1.000.000
Other thousand Roman numerals such as 4.000, 9.000, 40.000, 90.000, 400.000 and 900.000 can be seen in the table below.
IV IX XL XC CD CM
4.000 9.000 40.000 90.000 400.000 900.000
Roman Numbers Writing Rules
  • Roman numerals use a system of repetition, addition, subtraction and mixed combination.
  • Read the number from left to right.
Repetition rule
• 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

Addition rule
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

Subtraction rule
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
Mixed combination
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.

Break into Thousands, Hundreds, Tens and Ones.
Convert 1111 to Roman Numerals.
Break 1111 into 1000, 100, 10 and 1. Then do each conversion using table below.
  • 1000 = M
  • 100 = C
  • 10 = X
  • 1 = I
1000 + 100 + 10 + 1 = M + C + X + I
So 1111 = MCXI
Roman 1111 Numerals
Thousands
1000 M
2000 MM
3000 MMM
4000 I̅V̅
5000
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
Solved examples:

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.
Roman Numerals Chart
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.

Frequently Asked Questions
Q1 Is 3999 the highest Roman numeral?
The highest number that can be written is 3999 using standard or basic roman symbols, which is MMMCMXCIX.
Q2 How to write 4000 in roman number?
To write 4000 = I̅V̅ in roman numerals. a new symbol or a new rule, such as using an overline or called vinculum to indicate multiplication by 1000.
Q3 Roman numerals 35?
Roman numeral writing for 35 is XXXV.
35 = X + X + X + V = 30 + 5 = 35
Q4 How to write the correct number 45?
The correct Roman numeral writing for 45 is XLV.
45 = XL + V = 40 + 5 = 45
Q5 What roman numerals that multiply to 35?
Example: I = 1 x 35 = 35 = XXXV (Read more about rule 9 of the password game here)