Roman Numerals and Writing Numbers in Words
Writing & text · October 17, 2026 · 2 min read
Two old ways of writing numbers still turn up today: Roman numerals on clocks, film credits and book chapters, and numbers spelled out in words on cheques and contracts. Both follow clear rules.
The Roman numeral symbols
- I is 1, V is 5, X is 10.
- L is 50, C is 100.
- D is 500, M is 1,000.
How to read and write them
Symbols are added from largest to smallest, so VIII is 5 + 3 = 8. When a smaller symbol comes before a larger one, it is subtracted: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400 and CM is 900. Only I, X and C can be subtracted, and only from the next two larger symbols. A symbol isn't repeated more than three times in a row.
To write a number, split it by place value and convert each part. The year 2026 is 2000 (MM) plus 20 (XX) plus 6 (VI), which makes MMXXVI. The standard system covers 1 to 3999, because there is no accepted symbol for 5,000. The Roman Numeral Converter goes both ways and tells you when a numeral isn't written in the standard way.
Why numbers are written in words
Spelling out an amount is harder to alter than digits, which is why cheques and legal documents ask for it. Turning 123 into one hundred twenty-three is easy, but long numbers and amounts of money have rules of their own.
Rules for numbers in words
- Hyphenate the tens and ones from 21 to 99, such as forty-two.
- American English usually leaves out the and in one hundred twenty-three, while British English often writes one hundred and twenty-three.
- A billion is a thousand million in modern English. Older British usage meant a million million, which is why some texts differ.
- For money, write the whole amount in words and the cents as a fraction, like one hundred dollars and 50/100.
The Number to Words tool follows these rules, supports several currencies, and writes negative numbers and decimals too.