Roman Numeral Conversion : Definition, Conversion Rules

Safalta expert Published by: Yashaswi More Updated Sat, 19 Feb 2022 11:25 AM IST

Highlights

Check out the definition, calculations and conversion rules of Roman Numerals here at Safalta.com

Roman numerals are the symbols that are used in a system of numerical notation based on the ancient Roman system. These numerals are a combination of letters that are used to represent numbers. An example of a roman numeral is XLVII which is equivalent to 47 in numeric form. Roman numerals are denoted using a different combination of symbols, that include English alphabets. For example, 5 in roman numeral is denoted by V. It has wide applications in naming anything such as Class I, Class II, Class X, etc.

Source: Safalta.com

In this lesson, we will learn how to convert a given number to its Roman numeral and the conversion of Roman numerals to numbers. 


Table Of Contents-
1. Roman Numeral Conversion
2. Roman Numerals Calculation
3. Converting a Date to Roman Numerals
4. Converting Numbers to Roman Numerals
5.

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Roman Numerals Example


 

Roman Numerals Conversion

A number in Roman Numerals is a collection of the symbols (or letters/characters) C, D, I, L, M, V, X has written in a specific order (e.g. M’sM’s first, followed by D’sD’s, C’sC’s etc.). Generally, a subtractive notation is used in some cases to avoid four characters being replicated in sequences, such as IIII or XXXX, as shown below.

  • If “I” is placed before V or X, it represents one less, then four is IV (one less than 5), and 9 is IX (one less than 10)
  • If “X” is placed before L or C, it represents ten less, then 40 is XL (10 less than 50), and 90 is XC (10 less than 100)
  • If “C” is placed before D or M, it represents a hundred less, then 400 is CD (100 less than 500), and 900 is CM (100 less than 1000)

Also Read-  CM To Inches (cm to in) Converter

 

Roman Numerals Calculation

The below table shows the calculations to get the number for a given roman numeral.

Roman Numeral

Calculation to get the number

Roman Numeral

Calculation to get the number

I

1 = 1

XXXVI

10 + 10 + 10 + 5 + 1 = 36

II

1 + 1 = 2

XXXVII

10 + 10 + 10 + 5 + 1 + 1 = 37

III

1 + 1 + 1 = 3

XXXVIII

10 + 10 + 10 + 5 + 1 + 1 + 1 = 38

IV

5 – 1 = 4

XXXIX

10 + 10 + 10 – 1 + 10 = 39

V

5

XL

-10 + 50 = 40

VI

5 + 1 = 6

XLI

-10 + 50 + 1 = 41

VII

5 + 1 + 1 = 7

XLII

-10 + 50 + 1 + 1 = 42

VIII

5 + 1 + 1 + 1 = 8

XLIII

-10 + 50 + 1 + 1 + 1 = 43

IX

10 – 1 = 9

XLIV

-10 + 50 – 1 + 5 = 44

X

10

XLV

-10 + 50 + 5 = 45

XI

10 + 1 = 11

XLVI

-10 + 50 + 5 + 1 = 46

XII

10 + 1 + 1 = 12

XLVII

-10 + 50 + 5 + 5 + 1 = 47

XIII

10 + 1 + 1 + 1 = 13

XLVIII

-10 + 50 + 5 + 1 + 1 + 1 = 48

XIV

10 – 1 + 5 = 14

XLIX

-10 + 50 – 1 + 10 = 49

XV

10 + 5 = 15

L

50

XVI

10 + 5 + 1 = 16

LX

50 + 10 = 60

XVII

10 + 5 + 1 + 1 = 17

LXX

50 + 10 + 10 = 70

XVIII

10 + 5 + 1 + 1 + 1 = 18

LXXX

50 + 10 + 10 + 10 = 80

XIX

10 – 1 + 10 = 19

XC

-10 + 100 = 90

XX

10 + 10 = 20

C

100

XXI

10 + 10 + 1 = 21

CC

100 + 100 = 200

XXII

10 + 10 + 1 + 1 = 22

CCC

100 + 100 + 100 = 300

XXIII

10 + 10 + 1 + 1 + 1 = 23

CD

-100 + 500 = 400

XXIV

10 + 10 – 1 + 5 = 24

D

500

XXV

10 + 10 + 5 = 25

DC

500 + 100 = 600

XXVI

10 + 10 + 5 + 1 = 26

DCC

500 + 100 + 100 = 700

XXVII

10 + 10 + 5 + 1 + 1 = 27

DCCC

500 + 100 + 100 + 100 = 800

XXVIII

10 + 10 + 5 + 1 + 1 + 1 = 28

CM

-100 + 1000 = 900

XXIX

10 + 10 – 1 + 10 = 29

M

1000

XXX

10 + 10 + 10 = 30

¯¯¯¯VV¯

5000

XXXI

10 + 10 + 10 + 1 = 31

¯¯¯¯¯XX¯

10000

XXXII

10 + 10 + 10 + 1 + 1 = 32

¯¯¯¯LL¯

50000

XXXIII

10 + 10 + 10 + 1 + 1 + 1 = 33

¯¯¯¯CC¯

100000

XXXIV

10 + 10 + 10 – 1 + 5 = 34

¯¯¯¯¯DD¯

500000

XXXV

10 + 10 + 10 + 5 = 35

¯¯¯¯¯¯MM¯

1000000


 

Converting a Date to Roman Numerals


We can use roman numerals to represent the date of the day. Let us take the format to represent the date as MM-DD-YYYY (Month-Day-Year). The date 12-20-2019, for example, is written as XII-XX-MMXIX.

The years of the twenty-first century can be readily written as shown below.

2001 = MMI

2002 = MMII

2003 = MMIII

2004 = MMIV

2005 = MMV

2006 = MMVI

2007 = MMVII

2008 = MMVIII

2009 = MMIX

2010 = MMX and so on

 

Converting Numbers to Roman Numerals


To convert numbers to roman numerals, we must first divide the provided number into two groups based on the numerical value or place value of the digits. Any number can be converted to a roman form, and any roman form can be converted to a number. The example below will help you comprehend the aforementioned conversion.

 

Roman Numerals Example

 

Example 1:

Convert the number 1786 into the form of a roman numeral.

Solution:

First we need to split 1786 into thousands, hundreds, tens and units.

1786 = 1000 + 700 + 80 + 6

1000 = M

700 = DCC

80 = LXXX

6 = VI

Therefore, 1786 = MDCCLXXXVI
 

Example 2:

Convert the number 9143 into the roman numeral.

Solution:

Let us split 9143 into thousands, hundreds, tens and units.

9143 = 9000 + 100 + 40 + 3

9000 = ¯¯¯¯¯¯¯IX

100 = C

40 = XL

3 = III

Therefore,

9143 = ¯¯¯¯¯¯¯IX CXLIII

 

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