Class 4 - Maths - Roman Numerals

Learning Objectives

Recognise the basic Roman numeral symbols and their values.
Understand the rules for writing Roman numerals: repetition, addition, and subtraction.
Read and write Roman numerals from 1 to 50.
Convert between Roman numerals and Hindu-Arabic numerals.
Identify where Roman numerals are used in everyday life.

Let Us Begin!

Have you ever looked at a clock with letters like I, V, and X instead of numbers? Or noticed that some books write "Chapter IV" instead of "Chapter 4"? These are Roman numerals -- a number system invented by the ancient Romans thousands of years ago.

We use Hindu-Arabic numerals (1, 2, 3, 4...) in our daily life. These numerals were invented in India and later spread to the world through Arab traders. But Roman numerals are still used in many places. Let us learn how to read and write them!

Basic Roman Numeral Symbols

There are seven basic symbols in the Roman numeral system. For Class 4, we will focus on the first four:

Roman Symbol	Hindu-Arabic Value
I	1
V	5
X	10
L	50

Rules for Writing Roman Numerals

Rule 1 -- Repetition: A symbol can be repeated up to 3 times to add its value. But V and L are never repeated.

I = 1, II = 2, III = 3, X = 10, XX = 20, XXX = 30

Rule 2 -- Addition Rule: When a smaller value symbol is written after (to the right of) a larger value symbol, we add the values.

VI = 5 + 1 = 6, XI = 10 + 1 = 11, XV = 10 + 5 = 15, XXXVII = 10 + 10 + 10 + 5 + 1 + 1 = 37

Rule 3 -- Subtraction Rule: When a smaller value symbol is written before (to the left of) a larger value symbol, we subtract the smaller from the larger.

IV = 5 - 1 = 4, IX = 10 - 1 = 9, XL = 50 - 10 = 40

Think about it: Why do we write 4 as IV and not IIII? Because the rule says a symbol can be repeated only up to 3 times. So we use the subtraction rule instead.

Roman Numerals from 1 to 50

Number	Roman	Number	Roman	Number	Roman	Number	Roman	Number	Roman
1	I	11	XI	21	XXI	31	XXXI	41	XLI
2	II	12	XII	22	XXII	32	XXXII	42	XLII
3	III	13	XIII	23	XXIII	33	XXXIII	43	XLIII
4	IV	14	XIV	24	XXIV	34	XXXIV	44	XLIV
5	V	15	XV	25	XXV	35	XXXV	45	XLV
6	VI	16	XVI	26	XXVI	36	XXXVI	46	XLVI
7	VII	17	XVII	27	XXVII	37	XXXVII	47	XLVII
8	VIII	18	XVIII	28	XXVIII	38	XXXVIII	48	XLVIII
9	IX	19	XIX	29	XXIX	39	XXXIX	49	XLIX
10	X	20	XX	30	XXX	40	XL	50	L

Key Words and Meanings

Word	Meaning
Roman numerals	A number system using letters (I, V, X, L) invented by ancient Romans
Hindu-Arabic numerals	The number system (1, 2, 3...) invented in India and used worldwide today
Repetition rule	A Roman symbol can be repeated up to 3 times (I, X can repeat; V, L cannot)
Addition rule	Smaller symbol after larger symbol means add (VI = 5 + 1 = 6)
Subtraction rule	Smaller symbol before larger symbol means subtract (IV = 5 - 1 = 4)

How to Convert Hindu-Arabic to Roman Numerals

Break the number into parts and write the Roman numeral for each part:

Example: Convert 27 to Roman numerals

27 = 20 + 7 = XX + VII = XXVII

Example: Convert 44 to Roman numerals

44 = 40 + 4 = XL + IV = XLIV

Example: Convert XXXIX to Hindu-Arabic

XXXIX = XXX + IX = 30 + 9 = 39

Where Do We See Roman Numerals?

Roman numerals are used in many places around us:

Clocks and watches: Many wall clocks in Indian homes show hours as I, II, III... XII.
Books and chapters: Textbooks often number chapters as Chapter I, Chapter II, etc.
Competitions and ranks: Winners are shown as I (first), II (second), III (third) in school sports day.
Class numbers: Some schools write Class IV instead of Class 4.
Historical dates: Important years on monuments and buildings are sometimes written in Roman numerals.
Olympiad and quiz names: Science Olympiad Level I, Level II, etc.

Think about it: Look at the clock in your classroom or home. Does it use Roman numerals or Hindu-Arabic numerals?

Key Points to Remember

Basic symbols: I = 1, V = 5, X = 10, L = 50.
Repetition: A symbol can repeat up to 3 times (III = 3, XXX = 30). V and L never repeat.
Addition: Smaller after larger means add (VII = 5 + 2 = 7).
Subtraction: Smaller before larger means subtract (IV = 5 - 1 = 4, XL = 50 - 10 = 40).
To convert, break the number into parts and write each part in Roman numerals.
Hindu-Arabic numerals (1, 2, 3...) were invented in India.

Practice Questions

A. Fill in the Blanks

The Roman numeral for 5 is .
XL stands for the number .
The number 29 in Roman numerals is .
In the subtraction rule, a smaller symbol is placed a larger symbol.
The Hindu-Arabic numeral system was invented in .

B. Convert to Roman Numerals

14 =
23 =
36 =
45 =
49 =

C. Convert to Hindu-Arabic Numerals

XVII =
XXIV =
XXXVIII =
XLII =
XLIX =

D. Multiple Choice Questions

Which Roman numeral is NEVER repeated?
(a) I(b) X(c) V(d) None of these
What is the value of XLIV?
(a) 54(b) 44(c) 46(d) 34
Which is the correct Roman numeral for 19?
(a) XVIIII(b) IXX(c) XIX(d) XIIIIIIIII

E. Short Answer Questions

Write the three rules for forming Roman numerals.
Write any three places where you see Roman numerals in daily life.

Think and Do -- Fun Activity

Roman Numeral Clock: Draw a clock face in the circle below. Write all 12 hours using Roman numerals (I to XII). Then draw the hour and minute hands to show your favourite time of the day.

(Draw your Roman numeral clock here)

My favourite time: ____________

In Roman numerals: ____________

Why I like this time:

Mathematics -- Class 4

Mathematics -- Class 4 (continued)