**Year 4 Maths – Roman Numerals I to C** *KS2 Revision*

## What you need to know

**Things to remember:**

- If there is an I before a V or X it means subtract 1.
- If there is an X before L or C it means subtract 10.
- You should start by looking for any subtractions first.
- Add after subtracting.

Where we use 10 numbers to make up all other numbers, the Romans used a combination of 7 letters to write theirs. We will look at 5 of those letters:

Roman Numerals I V X L C

Numbers 1 5 10 50 100

The Romans had rules for how they wrote their numbers.

**Rule 1: Big Numbers Before Small, Add Them All Together**

II

1+1=2

III

1+1+1=2

VIII

5+1+1+1=8

XVII

10+5+1+1=17

XXXVI

10+10+10+5+1

CLII

100+50+1+1=152

The Romans didn’t like to put four of the same letter next to each other, so how could they write the number 4? They had subtraction rules.

**Rule 2: If there is an ****I**** before a ****V**** or an ****X****, we subtract 1.**

IV

5-1=4

IX

10-1=9

**Rule 3: If there is an ****X**** before an ****L**** or a ****C****, we subtract 10.**

XL

50-10=40

XC

100-10=90

We can use these rules to make our numbers up to 100. We just need to remember Rules 2 and 3.

4 = IV

9 = IX

40 = XL

90 = XC

XXIV

10+10+5-1=24

LXXVI

50+10+10+5+1=76

LXXIX

50+10+10+10-1=79

We don’t just read Roman Numerals, but we also need to know how to write them.

“What is 97 in Roman Numerals?”

We can do this in 3 steps.

**Step 1: **Think about how to write the tens:

90 = XC

**Step 2: **Think about how to write the units:

7 = VII

**Step 3: **Put **Steps 1** and **2** together:

97 = XCVII

## Example Questions

**Question 1:** What is XLIV in numbers?

Remember, an I before a V means subtract 1, and an X before and L means subtract 10.

XL = 50 – 10 = 40

IV = 5 – 1 = 4

After putting these together, we get that XLIV = 44.

**Question 2:** What is 99 in Roman Numerals?

Start with the tens:

90 = XC

Do the units:

9 = IX

Put them together:

99 = XCIX

99 in Roman Numerals is XCIX.