It seems like a stupid question, doesn’t it? You just… write them, don’t you? Well, yes, but there are some guidelines you can follow too.
Before we go any further though, let me state that these are just guidelines, and you can do whatever you want. Though I do recommend being consistent at least.
The main thing to consider is whether to use numerals or words. There are two general schools of thought on this. The first, which I subscribe to, is that you should write out the numbers between one and ten, and use numerals for all larger numbers. I suppose you could extend this to numbers up to twenty, as they’re all one word, and everything after requires two or more words. The other school of thought is quite similar, but suggests writing out all numbers up to one hundred, and then changing to numerals, as all larger numbers require four words or more (unless you’re American and say things like three hundred fifty, but even then I think you’d probably still write three hundred and fifty).
Obviously these guidelines are to make things easier for you when writing, saving time writing out complete words. It’s also easier for your readers too, as it’s much quicker for them to recognise a large number at a glance when it’s depicted with numerals. It’s much easier to pick out important numbers in a text too.
Those are the basics, but there are a few more specific guidelines too.
- Use commas with numbers in the thousands or more. Makes sense, as it makes it easier to identify the value of a number with a lot of digits. Though personally I like to use words when dealing with millions or higher, as it’s quicker to understand than counting zeroes (though for a number without many zeroes, like four million, nine-hundred and eighty three thousand, four-hundred and sixty-eight, 4,983,468 is obviously better.
- Don’t write the name of a currency after also using the sign. €14, not €14 euros, for example. In fairness, I think when people do this it’s basically a typo caused by the fact that when we speak, we say the name of the currency after the amount, but when we write we put the symbol before the amount, so we still have the instinct to write out the word after the amount that we say in our head.
- Hyphens! I like hyphens. They’re very useful with numbers. Such as joining the two parts of a two-digit number, if you ever have to write one out: forty-eight, for example. They’re also quite useful when modifying a noun with a unit of measure. That sounds hideously complicated, but it simply means doing something like this:
I have a 12-year-old nephew.
The prison is surrounded by a 15-metre wall.
Note that here I’ve used numerals, but sometimes it’s best to change to word to avoid confusion. For example:
I have 2 twelve-year-old nephews. Or, two 12-year-old nephews.
The prison is surrounded by 4 fifteen-metre walls. Or, four 15-metre walls.
You can find lots of other specific rules and recommendations, but I think you’ll do fine with what I’ve mentioned here. The main things are to be clear and consistent. If you write something that you think would be improved by changing numerals to words or vice versa, then make that change.
This post was inspired by yesterday’s by the way, when I realised that I was referring to numbers a bit and probably wasn’t being consistent. Please feel free to go back there and find examples of me not practising what I’m preaching here.