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P6 Mathematics - Term I

Topic 2: Whole Numbers

Lesson 4: Introduction to Roman Numerals

Duration: 45 minutes

Today's Learning Objectives for Roman Numerals

By the end of this lesson, you will be able to:

  • Identify the seven Roman numeral symbols
  • State the value of each symbol
  • Apply addition and subtraction rules
  • Convert between Roman and Hindu-Arabic numerals

Have You Seen Numbers Like These?

I, II, III, IV, V...

Where have you seen numbers like this?

  • Clock faces
  • Movie titles (Rocky IV)
  • Chapter numbers
  • Building dates

What Exactly Are Roman Numerals?

Numbers used by ancient Romans over 2,000 years ago!

They use LETTERS instead of digits.

And we still use them today!

The Seven Basic Roman Symbols

The seven Roman numeral letters I, V, X, L, C, D, M shown with their values

These are the building blocks of ALL Roman numerals!

Learning What Each Symbol Is Worth

Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1,000

A Memory Trick for the Symbols

I Value Xylophones Like Cows Do Milk

I = 1, V = 5, X = 10
L = 50, C = 100, D = 500, M = 1,000

Two Important Rules to Start

  1. Always write in CAPITAL LETTERS

    • Correct: IV, X, M
    • Incorrect: iv, x, m

  2. There is NO ZERO in Roman numerals!

The Addition Rule for Combining Symbols

When a smaller value comes AFTER a larger value:

ADD them together!

Examples of the Addition Rule

Roman Calculation Value
VI 5 + 1 = 6
XI 10 + 1 = 11
XV 10 + 5 = 15
LX 50 + 10 = 60

You Can Repeat Some Symbols

Repeat I, X, C, or M up to three times:

Roman Value
II 2
III 3
XXX 30

The Subtraction Rule for Combining Symbols

When a smaller value comes BEFORE a larger value:

SUBTRACT the smaller from the larger!

Examples of the Subtraction Rule

Roman Calculation Value
IV 5 - 1 = 4
IX 10 - 1 = 9
XL 50 - 10 = 40
CM 1000 - 100 = 900

How Position Changes Everything Here

IV ≠ VI

  • IV = 5 - 1 = 4 (subtract)
  • VI = 5 + 1 = 6 (add)

The position of the smaller number changes everything!

Which Symbols Are Allowed to Subtract?

Only I, X, and C can subtract:

Subtract From Example
I V or X IV, IX
X L or C XL, XC
C D or M CD, CM

Combinations That Are Never Allowed

  • VX (V cannot be used for subtraction)
  • LC (L cannot be used for subtraction)
  • IIII (use IV for 4 instead)
  • VV (never repeat V, L, or D)

Roman Numerals for 1 Through 10

Number Roman
1 I
4 IV
5 V
9 IX
10 X

Your Turn: Find Each Value

What is the value of each Roman numeral?

  1. VII = ?
  2. XII = ?
  3. XIV = ?
  4. XIX = ?

Checking Your Value Answers Together

  1. VII = 5 + 1 + 1 = 7
  2. XII = 10 + 1 + 1 = 12
  3. XIV = 10 + (5 - 1) = 10 + 4 = 14
  4. XIX = 10 + (10 - 1) = 10 + 9 = 19

Your Turn: Write in Roman Numerals

Write these in Roman numerals:

  1. 3 = ?
  2. 8 = ?
  3. 15 = ?
  4. 40 = ?

Checking Your Roman Numeral Answers

  1. 3 = III (1 + 1 + 1)
  2. 8 = VIII (5 + 1 + 1 + 1)
  3. 15 = XV (10 + 5)
  4. 40 = XL (50 - 10)

Roman Numerals for Larger Numbers

Number Roman
50 L
60 LX
90 XC
100 C

Quick Quiz: Name This Numeral

Question 1:
What is the Roman numeral for 100?

Answer: The Symbol for One Hundred

The Roman numeral for 100 is C.

(Think: Century = 100 years!)

Quick Quiz: Find This Value

Question 2:
What is the value of LX?

The Answer: LX Equals Sixty

LX = 50 + 10 = 60

(L = 50, X = 10, smaller after larger = ADD)

Quick Quiz: Find Another Value

Question 3:
What is the value of XC?

The Answer: XC Equals Ninety

XC = 100 - 10 = 90

(X = 10, C = 100, smaller before larger = SUBTRACT)

Summary: The Seven Roman Symbols

I V X L C D M
1 5 10 50 100 500 1000

Addition: Smaller AFTER larger → ADD
Subtraction: Smaller BEFORE larger → SUBTRACT

Key Points Worth Remembering Today

  1. Seven symbols: I, V, X, L, C, D, M
  2. Always CAPITALS
  3. No zero in Roman numerals
  4. Position matters: IV ≠ VI
  5. Only I, X, C can subtract

Tonight's Homework on Roman Numerals

  1. Write all seven symbols and their values

  2. Convert to numbers: VIII, XIII, XL, LXX, XC

  3. Convert to Roman numerals: 3, 9, 15, 40, 90

  4. Find one real-life example of Roman numerals

Next Lesson Preview: Roman Numerals in Life

Tomorrow: Roman Numerals in Real Life!

We will practice reading:

  • Clock faces
  • Dates on buildings
  • Years (like 2025 = MMXXV)

Great Work Today on Roman Numerals!

You learned:

  • The seven Roman numeral symbols
  • Their values (1, 5, 10, 50, 100, 500, 1000)
  • The addition and subtraction rules

I, V, X, L, C, D, M - You've got this!

Lesson Credits and Curriculum Source

Created: November 30, 2025
Based on: NCDC P6 Mathematics Curriculum - Topic 2: Whole Numbers

Source: National Curriculum Development Centre (NCDC), Uganda

Available from: https://ncdc.go.ug/