Cardinal numbers

Cardinal numbers are the basic numbers that show how many of something there are (1, 2, 3). By contrast, ordinal numbers show the order of those things (1st, 2nd, 3rd).

The most contentious style question for numbers is whether to spell them out in words or use numerals in body text. It is also important to be consistent in formatting larger numbers. The ASG recommends using commas rather than spaces to separate digits.

Words or numerals
Generally use numerals for all numbers below a million
I only have 2 meetings today.
Around 250,000 protestors marched down Rundle Mall.

Traditionally, Australian style guides have recommended spelling out numbers ‘one’ to ‘nine’ and then moving to numerals from 10 and above. 

But we now have strong evidence that all numbers are actually easier to read and mentally process as numerals than as words. The ASG supports the shift towards the use of numerals over words in body text.

We are considering leases on 3 different properties.

There are 5 or 6 contenders for the ‘employee of the month’ award.

The only numbers to watch out for are ‘1’ and ‘0’, as there is a risk these numerals could be misread as the letters ‘l’ or ‘O’, depending on your font. Numerals may also look odd in common expressions.

Try to follow these examples:

Quantities and other measurements

  1 folder of documents

  1%

Times  1 am
Compound adjectives
  1-hour car wash
Comparative and parallel numbers
  The study found 1 in 15 participants had cheated.
Common expressions or idioms

  on the one hand

  zero to hero 

For more on the rationale behind the shift towards numerals, please see our dedicated Words or numerals entry.

Exceptions
Spell out numbers in these special cases
Five staff will be relocated to the Darwin office.
We expect hundreds of responses to our latest mailout.

As well as spelling out numbers in common expressions, the ASG recommends doing so in the following situations:

Numbers that start sentences

  Fifteen modules are due for release next month.

Numbers that represent inexact ideas

  We need to evaluate hundreds of documents.

Imprecise non-decimal fractions

  One-third of the products were damaged during shipping.

Consecutive numbers that may be confused

  The client booked three 3-hour coaching sessions.

Large numbers
Show numbers of 4 or more digits with commas, up to a million
3,124
$864,920
55 million

ASG style is to separate thousands with commas rather than spaces. 

The post went viral and was shared more than 52,000 times on social media.
The post went viral and was shared more than 52 000 times on social media.
In a digital world, spaces can pose particular problems with numbers breaking across 2 lines.
The post went viral and was shared more than 52
000 times on social media

For very large numbers, use the following formats. Don’t add a space between the numeral and the unit when shortened.

Body textTables and graphics

  960,000

  960k

  0.96 million

  $4.2 million

  $4.2m

  $4.2 m

  2 billion

  2b

  2,000 million

Negative numbers

Don’t leave a space between the minus sign and the numeral

–30.5
See also:   Number formatting,  Numbers,  Ordinal numbers,  Words or numerals,  Zero