Roman numerals
Look at a clock face, a film credit at the end of a movie, or the chapter numbers in a book. You'll often spot letters like I, V, X, L, C standing in place of numbers. That's the Roman numeral system — the way the ancient Romans wrote numbers more than 2 000 years ago. In Year 4 we learn to read and write them up to 100.
Why we still use them
Roman numerals stuck around for decoration and order. You'll find them on:
- clock and watch faces (IV, IX, XII for 4, 9, 12),
- the front matter of books (Chapter II, III, IV …),
- film and game sequels (Star Wars VII),
- monuments and gravestones (MCMXLV = 1945),
- monarchs' names (Queen Elizabeth II, Henry VIII).
For everyday arithmetic we use the Hindu-Arabic numerals (0–9) — Roman numerals are slow to add and have no zero. But they are still part of culture.
The seven symbols
Roman numerals use seven capital letters as symbols.
| Letter | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1 000 |
In Year 4 we only need the first five — I, V, X, L, C — because we work up to 100. The letters D and M will come in later years for bigger numbers.
A handy memory trick: I V X L C D M — "I Value X-rays Like Cats Drinking Milk." Silly, but it sticks.
Reading them — the basic idea
Each letter has a value, and you usually add them up.
- III = 1 + 1 + 1 = 3
- VI = 5 + 1 = 6
- XV = 10 + 5 = 15
- LXX = 50 + 10 + 10 = 70
- CL = 100 + 50 = 150
The letters are written from biggest to smallest, left to right. When that's the case, you just add.
The subtraction trick
There's one twist. When a smaller letter comes before a bigger one, you subtract instead of adding.
- IV = 5 − 1 = 4
- IX = 10 − 1 = 9
- XL = 50 − 10 = 40
- XC = 100 − 10 = 90
Without the subtraction trick, the Romans would have written 4 as IIII (1+1+1+1). Their shortened version IV is cleaner — and you'll often see it on watches (although some watch faces use IIII anyway, just for symmetry).
Only four subtractive pairs appear up to 100: IV, IX, XL, XC. There are more for bigger numbers (CD, CM), but they don't appear in Year-4 work.
What you will learn
- Reading Roman numerals — turning the letters into a number
- Writing Roman numerals — turning a number into letters
- Worked examples — practice up to 100
- For parents — games and tips at home