How to Write Numbers — The Basics
Ever stopped mid-sentence wondering whether to write “7” or “seven”? You’re not alone. This is one of those grammar questions that confuses even experienced writers. The good news is, once you understand the basics, it becomes second nature.
There are two ways to show numbers in writing. You either write the number in words like “five” or you use figures like “5.” Both can be right depending on the situation.
The biggest rule here is simple: stay consistent. If you start writing numbers one way, keep doing it throughout your whole piece. Jumping between styles randomly makes your writing look messy. Whether you’re writing for blogs, books, newspapers, or magazines, consistency always wins.
Writing Numbers — AP Style vs. Chicago Style
Here’s something interesting. The two biggest style guides in the world actually disagree on how to write numbers. So the rule for writing out numbers depends on which guide you follow.
AP Style (used mostly in news and journalism) says spell out numbers zero through nine, then use numerals from 10 onwards. So you’d write “three apples” but “15 oranges.”
Chicago Manual of Style (used in books and academic writing) says spell out numbers zero through one hundred. After that, use figures. It also says spell out whole numbers paired with words like hundred, thousand, or million so write “two hundred” but use figures for something like 2,347.
Neither is wrong, they just serve different purposes. The key is knowing which one your field or editor prefers, and then sticking to it.
When to Spell Out Numbers
No matter which style guide you follow, some rules are universal. Here’s what almost every writer agrees on.
Start of a sentence — always spell it out. If a number opens your sentence, write it in words. So instead of “23 students passed,” write “Twenty-three students passed.” AP Style does allow years as an exception though writing “2020 was a tough year” is perfectly fine.
Single-digit numbers in everyday writing look better spelled out. “I have two brothers” reads more naturally than “I have 2 brothers.” It just flows better in normal sentences.
Large round numbers are often cleaner in words. “About two million people attended” is much easier to read than “about 2,000,000 people attended.” But if the number is something specific like 2,040,086 use figures, no question.
When talking about decades, don’t capitalize them. Write “during the eighties and nineties” not “Eighties.” If you prefer using figures, write “the ’80s and ’90s” with an apostrophe before the number and no apostrophe before the “s.”
Rule for Writing Out Numbers — Core Rules Explained
These are the core rules for writing out numbers that every writer should know.
Hyphenate compound numbers from twenty-one through ninety-nine. Always. So “forty-three” is right, and “forty three” is wrong. The same goes for written-out fractions — write “two-thirds” and “one-half” with a hyphen. But phrases like “a half” or “a third” don’t need one.
Use commas in numbers with four or more digits. So 1054 becomes 1,054 and 2417592 becomes 2,417,592. Only count the actual digits, ignore the decimal point when placing commas.
Don’t use “and” in whole numbers. Write “one thousand one hundred fifty-four”, not “one thousand and one hundred fifty-four.” Save the word “and” only for decimal points, like “one hundred fifty-four dollars and sixty cents.” That “and” clearly signals the cents part.
Write decimals in figures, not words. Write “1.1 yards” not “one point one yards.” Also, always put a zero before the decimal point when the number is less than one, write “0.79 inches” not “.79 inches.” It prevents misreading, especially in technical content.
When accuracy really matters, use both forms together. In medical or legal writing, write the figure first, then spell it out in parentheses, like “Add 73 (seventy-three) grams.” This removes any chance of confusion.
How to Write Out Numbers in Special Contexts
Some situations come with their own rules. Here are the most common ones.
Time of day using figures is widely accepted. “The meeting starts at 9:00 AM” or “The train leaves at 6:22 a.m.” are both fine. AM and PM can be written multiple ways A.M., a.m., or am just pick one and stay consistent. For noon and midnight, spell those words out instead of writing 12:00 PM or 12:00 AM, since those can confuse readers.
Some writers still spell out time when using o’clock “She leaves at four o’clock” rather than “4 o’clock.” Both work fine depending on your writing tone.
Dates are simple. Write “June 30, 1934” or “the 30th of June, 1934.” When the date comes after the month, no suffix is needed just “June 30,” not “June 30th.”
Currency never write “$1,250 dollars.” The dollar sign already tells the reader it’s dollars, so adding the word is just repeating yourself. For amounts under a dollar, skip the sign entirely write “sixty cents” or “60 cents” instead of “$0.60.”
Percentages and mixed fractions go in figures for formal writing. Write “a 5 1/2 percent wage increase” rather than spelling it all out. If the fraction starts a sentence though, spell it out — “Five and one-half percent was the increase.”
Common Mistakes When Writing Numbers
Even careful writers slip up here. Watch out for these.
Mixing styles in the same sentence is the most common error. Writing “You can earn from one million to 5 million dollars” looks inconsistent. Keep it uniform either “one million to five million dollars” or “$1 million to $5 million.”
Wrong apostrophe use with decades trips a lot of people up. Many write “1980’s” when they mean the decade. The right form is “1980s” no apostrophe. Use an apostrophe only when letters are missing, like “’80s” where “19” has been dropped.
Writing “$50 dollars” is a redundancy that makes writing look careless. The dollar sign already does the job drop one or the other.
Quick Reference — Rules for Writing Out Numbers at a Glance
- Always spell out numbers that begin a sentence
- Hyphenate compound numbers from twenty-one to ninety-nine
- Hyphenate written-out fractions like two-thirds and one-half
- Use commas in numbers with four or more digits
- Put zero before a decimal point for numbers less than one
- Save “and” only for decimal points in written-out numbers
- Use figures for time, dates, currency, and percentages
- Never write “$100 dollars” — it’s one or the other
- Stay consistent throughout your entire piece
Conclusion
Getting the rule for writing out numbers right is not complicated once you know the basics. Whether you follow AP Style or Chicago Manual of Style, the real goal is always clear and consistent writing. Know your audience, pick your style, and stick with it. Small things like proper hyphenation, decimal formatting, and correct currency writing add up to content that feels professional and trustworthy.
Frequently Asked Questions
When Should You Spell Out Numbers in Formal Writing?
Spell out numbers one through nine in most formal writing. Always spell out any number that starts a sentence, no matter how large it is.
What Is the Rule for Writing Numbers in AP Style?
AP Style says spell out zero through nine and use numerals for 10 and above. For numbers over a million, write it as “2.5 million.”
Do You Always Hyphenate Written-Out Numbers?
Hyphenate compound numbers from twenty-one through ninety-nine and all written-out fractions like two-thirds. Don’t hyphenate casual terms like “a half.”
How Do You Write Out Large Numbers Correctly?
Spell out large round numbers like “two million” for easy reading. Use figures for specific numbers like 2,040,086 and always add commas every three digits.
Is It Wrong to Write “$50 Dollars”?
Yes, it’s redundant. The dollar sign already means dollars. Just write “$50” or “fifty dollars” — not both together.
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