I am editing a mystery that takes place in an apartment building. Various apartment numbers are referenced often. 503 is where the murder takes place. Everyone always says each digit when referring to the unit.

So... how should it be written? Five-o-three or 503 or five oh three?

Thanks in advance!!


3 Answers 3


In a style choice, choose familiarity.

Writing a fictional story is about communicating ideas to the reader. The words are not decorative like a certificate or signage, and they are not accurately phonetic like documentation or a language translation.

Idealy, the text should disappear as the reader becomes engaged. Try not to do awkward things with fonts or word-choice or spellings that would knock the reader out of their concentration.

Numbers as words

Certain numeric 'formats' are so familiar we recognize them out of context. You can easily guess which is the correct format (and which are very wrong) even without the spoiler reveal:

an address

503 Elm St
Five Ohh Three, Elm Street
Five-hundred-and-third Elm Street

a time

5:03 PM
503 P. M.
Five-oh-three, pee-emm

a phone number

Five-five-five twelve eleven
Five million, five-hundred and fifty-one-thousand, two-hundred and eleven

We read addresses and phone numbers as a 'number word', grasping them as a concept (a location) instead of a string of arbitrary digits –– other numbers (like bank accounts) feel like a string of arbitrary digits.

Information or Style

Some of my bad formats above are so un-familiar the brain trips over them. Maybe the eye needs to go back and re-read – it's so disruptive the actual information (the location) is hard to remember. That's almost always a bad thing.

Location names that follow convention are just easier to understand. Apartment 503 is directly above 403, and across the corridor from 504. These numbers don't feel arbitrary. In a murder mystery logistics should be important.

But there are always exceptions for style-choice where the style is the information –– "5 OH 3", "Fiddy-o'fee" –– the thing communicated is more than just the straight apartment number, it's a hint or a tell....

The usual advice is to pick a style and be consistent, but in a murder mystery some change in style might be a clue?

  • Thanks for the advice.
    – NoName
    May 4, 2023 at 17:30

It is correct to write 503 as "five zero three" or "five hundred and three".

But it is common to say "five oh three" for 503. So if the dialog is supposed to reproduce what people say it will probably be "five oh three".

  • Thanks for the advice.
    – NoName
    May 4, 2023 at 17:31

The common rule that I learned is that in fiction you write out numbers as words.

In its traditional form a narrative is something that someone can speak. Historically, tales were told, not read, and even today parents read books to children and many "readers" listen to audiobooks. Research has even found out, that the vast majority of readers subvocalize the text, that is, the muscles in the human vocal tract move while you are reading in the same way they would if you were speaking what you read, only less intensely. Suppressing subvocalization seems to hamper reading fluency and understanding.

For that reason, a traditional narrative must consist of what may be spoken – and the convention is to use the words the reader would speak right away, instead of symbols like numerical digits.

But there have always been nonverbal elements in written texts – such as the "plot lines" in Sterne's Tristram Shandy – and fiction has developed in recent years and today includes "unspeakable" elements such as meaningful formatting (for example as a Messenger conversation with smileys) more and more often.

Therefore, in my opinion, you are facing a choice: Do you want to write and format your text in a more traditional style? Then write numbers as words. Or do you want to use non-verbal elements for a specific effect? Then think about what effect you are trying to achive (for example, you might want to evoke a visual image of the room number in the mind of the reader) and write and format your text accordingly (for example, with numerical digits). But keep in mind that the more you deviate from convention, the more your reader might stumble over those deviations.

  • Thanks for the advice.
    – NoName
    May 4, 2023 at 17:31

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