The rules for numbers in general (not technical) content are:

• Use words for ‘zero’ and ‘one’. 
  – In some typefaces, it’s easy to confuse 0 and 1 with certain letters.
• Use numerals for ‘2’ and above. 
  – People find numerals easier to scan than words.
• Use a comma in numbers from 1,000. 
  – Screen readers will announce the numerals as a single number.
• Use numerals for large numbers when it’s important to be precise.
• Combine numerals and words for large, rounded numbers from a million. 
  – It’s easier to understand 1 million than 1,000,000.

Exceptions

There are some exceptions to the rule of using numerals for ‘2’ and above.

Journalistic style

Government writing that follows journalistic conventions can use words for numbers below 10. Media releases usually follow journalistic style.

Words to start a sentence

Use words for a number that starts a sentence. You can choose to rewrite the sentence if you want to use a numeral.

When to use numerals for ‘0’ and ‘1’, not words

In some contexts, we write ‘zero’ and ‘one’ as numerals, not words. For example, we use numerals for units of measurement (1.05 cm) and times of day (00:45 AEDT). Here are 2 more instances that often appear in your everyday writing.

Write ‘0’ and ‘1’:

• to compare numbers
• in a series of numbers.

Comparisons

Always compare numerals, not words and numerals.

Series of numbers

Always use numerals for a group of related items.

Style Manual pages

• Choosing numerals or words
• Numbers and measurements (section)