When it comes to writing, words are words; there is no question of whether you spell them out or not. Well, when it comes to numbers, you have the option of either spelling out the number or using the numeral. Can you use numerals whenever you want, or do you always have to spell them out? Believe it or not, there are rules on how to use them.
The standard rule of thumb is to write out every number that is 0–100 (or, I should say zero through one hundred.) Instead of writing a character in your story took 2 apples, you’d write they took two apples. Now, in fiction writing that can be expanded as you try to avoid using actual numerals unless the rule is explicit (you’ll see a little later a few of them). So if a character stole 1,000 CDs, you’d write that they stole a thousand CDs. Lean toward words instead of numbers every chance you get.
Now, onto the exceptions and confusing parts.
Date and Time
You don’t want to write out March seventh. It doesn’t look right, and readers will hesitate as they go along. Anything that makes your reader stop and think about if it needs to be removed or corrected. Write out March 7th ; that is easier to read and part of acceptable writing. Or you could write the seventh of March, which makes everyone happy.
What about years? Never write them out. Always use numerals when you are writing a year unless the character is saying the numbers individually for someone who doesn’t understand or to write the numbers down: “Nineteen…fifty….six.”
What about eras? That can be done either way though with fiction, writing it out usually prevails. You see more of “the 1700s” in academic and non-fiction writing. When it comes to fiction writing, you’ll usually see “the eighteenth century” used instead. Again, lean toward writing the numbers out if in doubt.
Time? Well, that is another one you’ll find debated across the fiction writing community. Technically, you can say 11:00 A.M. or eleven o’clock in the morning or even eleven in the morning and be perfectly fine. But if you look at most books you read, especially from the bestselling authors, they rarely use numbers unless they are quoting something in the novel. They typically write the time out. You can use whichever one you feel most comfortable with, but writing it out is done the most.
What about addresses? Just like dates, you should look at using numbers here. Why? Because that is what our eyes are used to. In reading a scene, we’d slow down when the character had to go to two-hundred sixty-nine West Kentwood Drive. That doesn’t look nor feel right. Reading it would go much smoother when you read “They went to 269 W. Kentwood Dr.” This is what we are most comfortable reading.
The same can be said about numbers that signify something specific like a road, room, building. You don’t go to Room Twenty; you go to Room 20. The character doesn’t race down highway fifty-two. He races down HWY 52. Again, it is what we are used to seeing. Now, keeping that in mind, the character will go to the fourth floor and not Floor 4. We really don’t see “Floor 4” when we go into buildings and that is not how we talk.
What if you are actually talking numbers here? In non-fiction writing, you should be careful here. A percentage can be done in numerals. In fiction writing, technically you can also say 15 percent or 15%, but like time you’ll generally see it written out as “fifteen percent.”
You can also keep in mind that in non-fiction it is generally acceptable to write out numbers and then put the numeral equivalent in parentheses next to it for clarification. Don’t do that in fiction writing. It is too formal and stiff for readers.
And 0? Always say ‘zero’. If he came up with 0 leads, say ‘zero.’
When you are writing your fiction story, lean to writing out the numbers unless you are mentioning a specific location or an address. If in doubt, reference the Chicago Manual of Style but keep in mind that what might be ‘acceptable’ might not be received well by fiction readers as the CMS deals with Non-fiction and fiction.