One vs. 1
I'm prefacing this tiny writing lesson with an acknowledgement that 90% of people will not care or even notice how you write numbers. But it's the kind of thing that's good to know so you can ignore it.*
When you write numbers, you can either write them as words (one) or numerals (1). But when is it numeral time and when is it word time?
For the purposes of this lesson, we're going to take cues from the AP Style Guide (used by American journalists) and the Australian Style Guide (used by Australian anyones). The way style guides deal with numbers has changed in the last few years because we’re all so freakin’ online. Many people believe that style guides are moving towards predominantly using numerals, for ease of reading on small phone screens, but written out numbers still have a place in formal writing so let’s start there. ** More on style guides in a later edition, they are a very boring topic so I'm delaying it for all our sakes.
The rule, according to the AP, is if the number is nine or under, write it out in letters. When it's 10 or over, write it out in numerals.
There are, of course, annoying exceptions to this rule.
The exceptions
Use letters when you are:
Starting a sentence, subject line, or headline.***
For example: Twelve swans have been released into your bedroom.
Referring to expressions that aren't exact.
For example: The number of swans involved in the bedroom incident has been updated to hundreds.
Referring to inexact fractions.
For example: Around one-third of swans in your bedroom have diarrhoea.
Dealing with a number pile up and it's getting confusing.
For example: Thankfully, the Kmart near you still has three 3-layer swan-catching nets available.
Using an expression.
For example: “I should not have left of a big box of aquatic vegetation, the preferred food of a swan, open in my room. But hindsight is twenty-twenty," you say, teetering on the brink of hysteria, as you are honked at by a trapped swan.
Anytime you use zero.
For example: Defeated, you walk over the "Days without a swan incident" counter and reset it to zero.
Use numerals when you are:
Referring to a time.
For example: When your alarm went off at 8:15 am this morning, some of the swans had managed to get back into your room and were, once again, eating your mattress.
Referring to a percentage.
For example: Up to 75% of your ornate Lush bath bombs had also been eaten during the swans’ second foray.
Referring to a date or a time.
For example: The swan exterminator called to say he has an available appointment next year on 5 December at 1 am.
Referring to money.
For example: To prevent this from happening again, you spent $4,000 on an early swan detection system.
Referring to temperature, speed, distance, weight, highways, age, and addresses.
For example: 30°C. 60 kilometers per hour. 100 meters. 50 kilograms. Route 66. 28 years old. 123 Fake Street. It's hard to make this one work with the swan narrative, sorry. But these things just feel like they should be written as numerals, right? They have big numeral energy.
These are, I think, just the most common situations you'll encounter but tbh this is just the tip of the iceberg for numbers. There are lots of different exceptions and rules for writing numbers and most of them should not worry you.
*I do not believe that knowing how to format numbers will make you a better writer. I do believe that being confident in your writing will make you a better writer and part of being confident is not fearing that there’s a whole world of rules out there that you know nothing about. Once you know the rules, whether you apply them or not, you can quiet that part of your brain that says you don’t know enough about grammar to be a good writer or your writing is somehow incorrect.
**The Australian Style Guide says numerals are easier for people to read and comprehend, especially on screens and in a rush, so they're moving towards using numerals more than words. Their official recommendation is to use numerals for anything under a million. The AP stands firm on the 'under nine, write the word' rule. I follow the AP but that’s a personal choice stemming from my journalism degree. Choosing a style guide is a very political and personal decision but in the end, it is a question of style, not correctness. Whatever you choose, choose with the reader in mind and follow your guide consistently.
***The only exception to this is when using the year.
For example: 2022 was the year of the swan diarrhea incident.