Spelling out numbers
- Spell out zero through nine in narrative formats.
- Always spell out a number at the beginning of a sentence. Consider rewriting sentences to avoid awkwardness; e.g. “The year 2020 was full of surprises,” not “Twenty-twenty was full of surprises.”
- The above apply to both cardinal and ordinal numbers (first, second, 10th, 21st)
- Spell out very large numbers in narrative contexts (four million, 10 billion)
Use numerals for:
- 10 and above
- Addresses (unless the specific street spells them out; e.g. Ninth Street)
- Ages (She was 9 years old)
- Dates, years, decades (May 4, the 1998 reprint, the 1990s). Note that ordinal numbers are never used for dates (May 4, not May 4th), but they are used for centuries (the 21st century).
- Percentages (5 percent)
Currency
- Use the currency symbol and numeral for all specific amounts ($1, not one dollar).
- Spell out very large numbers, even when under 10 ($4 million, $2 billion)
- Never use both the currency symbol and the word, it’s redundant ($1 million, not $1 million dollars).
- Use the word for general concepts (the project will cost several million dollars).