How we write numbers – and why

Three or 3? Six million, 6m or 6,000,000? For many editors, checking that numbers are written correctly – or at least consistently and wisely – is an everyday part of the job. This is especially true when we’re working on business material. Let’s take a look at the different ways of writing numbers, and some reasons why it shouldn’t always be done in the same way.

Writing numbers – that’s simple, isn’t it? You just use those keys from 1 to 0 near the top of the keyboard, or that number pad on the right.

If only it were that simple. Very often, it’s better to use words instead of numerals. If you’re writing for someone else, they might expect you use words in some situations.

As with so many things in the world of writing, this is mainly about style choices – and adapting your style to suit the type of material, its purpose, its context and its target audience.

The ‘what’

First, we need to consider what kind of number we’re writing, and what it refers to …

• Exact whole numbers are usually written in words if they’re no higher than a chosen limit, which is usually either nine, ten, twenty, ninety-nine, a hundred or possibly a thousand. We’re unlikely to see something like ‘1 or the other’ or ‘she was caught in 2 minds’ in anything that’s been professionally edited. Above that limit, we normally use numerals, at least until we get into the millions.
• Approximate numbers, even if they’re below a million, are sometimes best written in words: ‘about fifty’, ‘a few hundred’, ‘over a thousand’.
• For millions, billions and above, the exact figure isn’t usually stated. It’s more common to write something like ‘2 million’, ‘five million’, ‘half a billion’ or ‘3.4 billion’ (the form of words or numerals used at the start is also a matter of style choice), or use a shorter form such as ‘2.3m’ or ‘15bn’.
• Fractions might be fairly precise (‘6.2 kilometres’) or rough (‘around half of the population’). They also might be expressed as old-style ‘simple’, ‘common’ or ‘vulgar’ fractions (‘?’, ‘3?’), or in decimal format (‘0.24’, ‘12.5’). The former are often written in words (‘two-thirds’, ‘seven-eighths’) – but not so much the latter, except perhaps in dialogue (‘“The reading is down to four point six!”, he cried.’).
• Numbers used with measurements are also often treated differently: they’re more likely to be in numeric form. So we might write both ‘five cities’ and ‘5 miles’ in the same piece of work, without straying from the required style. If the unit of measure is abbreviated, a number in word form would look silly: ‘It was seven km away.’

The ‘why’

So, what’s the point in all this variation? And how do we, or the people we’re writing or editing for, choose a style?

These aren’t just arbitrary rules. Words work better in some contexts, numerals in others. They each have their advantages and drawbacks.

Why use words?

• They help to make the text look neater and more attractive – more important in some types of writing than others.
• They make for a smoother reading experience. Numerals can be distracting, grabbing more attention than they should – just like capital letters and some symbols (‘&’, for example).

Why use numerals?

• If the numbers are especially important, and particularly if you want the reader to compare or contrast them with each other, using numerals will make them easier to grasp.
• Large numbers can be difficult to absorb if they’re written in words. For example: ‘She won three hundred and twenty-nine votes, in contrast to her opponent’s two hundred and eighty-three,’ or, ‘The club’s average attendance rose by thirteen thousand, nine hundred and twenty-six, to forty-seven thousand, eight hundred and ninety-four.’ Got that?

In fiction, numbers tend to be used less, and to be less significant, than in non-fiction writing. And, in a book that’s going to be read for pleasure rather than out of necessity, it’s important to make the pages look appealing. This means minimising things that might ‘jump off the page’ and have a jarring effect – including numerals – if they’re to be used at all. So, it’s common for most, or even all, types of numbers to appear in word format.

The same applies to the more creative, literary end of the non-fiction spectrum. The reader should be allowed to get swept along in the narrative, with the visual aspects of the book giving them as few jolts as possible.

However, it’s a different story with writing that revolves around hard facts, such as business, technical or instructional material, and sometimes (depending on the subject) in academic or educational content as well. Here, numbers often play a big role in getting the message across, and there’s nothing wrong with making them stand out. You might well want the reader to absorb the numbers quickly, and perhaps compare or contrast them with each other. Making the pages look pretty is less of a priority. In tables, charts and diagrams, especially, numerals make a stronger impact than words.

Odds and ends

In almost any kind of writing, a number that acts as an identifier is usually written in numerals – for example, the number of a chapter in a book, or of a house on a named street.

It’s generally agreed that we should avoid starting a sentence with one or more numerals. This can look a bit odd, and in some contexts, the number might be mistaken for a section or paragraph reference.

There are some grey areas, such as when numbers above and below the words-to-numerals limit are used close together and in a closely related way. For example: ‘Their children were aged nine and 11.’ This can look a bit odd and jarring, and some style guides recommend choosing one style for both or all of the numbers – but others suggest that it isn’t enough of a problem to warrant breaking the usual rule.

And there are other related style issues that I won’t go into here, just to keep this thing fairly brief: commas in numbers above 999 (‘2,485’ vs ‘2485’), ordinal numbers (‘5th’ vs ‘fifth’), elision (‘341–5’, ‘341–45’ or ‘341–345’), dates, times, money amounts, percentages, sport scores, phone numbers.

Mind how you go

All in all, it’s worth paying attention to the way you write numbers: it makes a difference to the readability and impact power of the material you’re writing. There are no universally ‘right’ or ‘wrong’ ways, but following sensible guidelines can help you get the right balance between clarity and ease of reading, according to what you’re writing, who you’re writing it for, and why.

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(Originally published as a blog post.)