How to Write Numbers in Text: The Rules That Actually Matter
Spell it out or use digits? The rules vary by style and context. Here is how to handle numbers consistently.
Numbers Are Where Style Guides Disagree
Few questions trip up writers more than whether to write seven or 7. The answer depends on which style guide you follow, and the major guides do not all agree. That is not a flaw. It means the first decision is which guide your publication uses, and then you apply its rules without exception.
What matters more than any single rule is consistency. A reader may not know AP from Chicago, but they notice when you write three in one paragraph and 3 in the next. Pick a system and apply it the same way every time, and your writing looks professional even to readers who could not name the rule.
The Two Big Approaches
AP Style, common in journalism and news, spells out numbers one through nine and uses figures for 10 and above. It favors digits because they scan fast in news copy and save space in tight layouts.
The Chicago Manual of Style, common in books and academic writing, spells out numbers up to one hundred, and uses figures for 101 and above. It favors words because prose reads more smoothly without numerals breaking the line. Neither is wrong. They serve different reading contexts.
AP vs. Chicago on Common Numbers
| AP Style | Chicago Style |
|---|---|
| one through nine spelled out | one through one hundred spelled out |
| 10 and up as digits | 101 and up as digits |
| always digits for ages, dates, money | ages usually spelled out in formal prose |
| percent spelled as % | percent spelled out in nontechnical text |
| millions as $5 million | millions as five million dollars |
Rules That Hold Across Most Guides
- 1Spell out a number that starts a sentence
Twenty people attended reads better than 20 people attended. If the number is long, reword the sentence so it does not open with it, rather than forcing an awkward spelled-out figure.
- 2Use digits for exact measurements, dates, and money
Quantities like 6 cm, July 4, 2021, or $42 stay as figures in nearly every guide. Precision and scannability matter more than prose smoothness here.
- 3Keep a category consistent
If you write one rule, write all the rules in that list the same way. Mixing spelled-out numbers and digits within the same sentence or list looks careless, even when each is technically correct.
- 4Never start with numerals back to back
Avoid constructions like 7 12-year-olds. Spell one out or reword so the reader is not staring at a string of digits.
If your publication does not have a house style, choose AP or Chicago and write it down somewhere visible. The single biggest source of number errors is writers switching guides mid-piece. Decide once, apply everywhere, and your copy looks clean.
Special Cases Worth Knowing
A few cases are stable across guides. Round numbers in casual phrasing are usually spelled out: a hundred people, not 100 people. Ordinals in formal prose follow the same rule as cardinals, so first through ninth in Chicago, but first through ninth spelled and 10th as a digit in AP.
Large numbers get a convention too. Write $5 million, not $5,000,000, in most business and news copy. In technical or financial reports, the full figure may be required for precision. Match the convention to the audience the piece serves.
Quick Consistency Checklist
- You know which style guide the piece follows
- The same threshold rule applies throughout, with no mid-piece switches
- No sentence starts with a numeral
- Ages, dates, money, and measurements are digits unless the guide says otherwise
- Numbers in the same sentence or list use the same format
The Numbers Game
The right way to write a number is the way you write every other number in the piece. Consistency reads as competence; inconsistency reads as carelessness.
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