What number is that?
Roman numerals turn up on clock faces, chapter headings, kings and queens, and at the end of films. Each spin shows one and asks what it is worth:
The rules, in one paragraph
- I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, M is 1000.
- Letters are added up from the left: XII is 10 + 1 + 1 = 12.
- A smaller letter before a bigger one is taken away: IV is 5 – 1 = 4, XL is 50 – 10 = 40.
- Only I, X and C are taken away, and only from the next two letters up.
- There is no zero, which is why the system disappeared from arithmetic.
Start easy
The wheel opens with the numerals on a clock face. Switch the second group on for the tens and hundreds, and the third for years – MCMXCIX is 1999 and takes a moment even when you know the rules:
For the classroom
Score and Best run are under the wheel, and Take the right ones off the wheel leaves only the ones still to learn: