How to Spell Numbers in Words (Complete Rules)
Last updated 19 June 2026
Spelling a number in words follows a small set of consistent rules. The short answer: write the number from the largest group down, hyphenate two-word numbers from twenty-one to ninety-nine, and group thousands, millions, and billions.
The core rules
- 0–20 are unique words: zero, one, two … twenty.
- Tens are twenty, thirty … ninety. Combine with a hyphen: twenty-one, sixty-seven.
- Hundreds read as “[digit] hundred”, e.g. three hundred. Add the rest after: three hundred forty-five.
- Groups of three (thousand, million, billion) are read left to right: 12,500 → twelve thousand five hundred.
British vs American “and”
British English inserts and before the final tens/units: one thousand and five. American English usually drops it: one thousand five. Both are widely understood; be consistent within a document.
Common mistakes
- Forgetting the hyphen (writing “twenty one” instead of “twenty-one”).
- Adding “and” in the wrong place in American style.
- Mixing digits and words for the same value in formal writing.
See the Chicago Manual of Style and AP Stylebook for house-style guidance on when to spell numbers out versus use digits.
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