How to Use Numbers in Writing

Writing numbers? ‘But that’s easy’, we hear you cry! However, not every student knows the rules that govern the use of numbers in academic documents. Unfortunately, not many people agree on these rules either!

Today, we’re going to look at some widely agreed upon approaches to using numbers in writing. We’ll be using illustrative excerpts from our fictional essay, ‘Aliens Among Us: A Study of Extra-terrestrials in Australia‘.

Using Numbers in Text

Any numbers below ten are generally written as text in academic documents. As such, in a sentence like this:

We used 7 groups in our study to test for aliens in the human population.

You should replace the number ‘7’ with the word ‘seven’:

We used seven groups in our study to test for aliens in the human population.

However, for numbers higher than ten, you should use numerals:

All in all, we found 7,182 aliens who had been posing as humans.

It’s also important to be consistent when more than one number appears in a sentence, even if this means bending the rules above so that you use the same format for both (usually numerals). For example:

Respondents were aged between seven and 82. – Inconsistent

Respondents were aged between 7 and 82. – Consistent

Remember to check your style guide on this, though, as some approaches recommend writing out numbers up to 100!

Statistics and Measurements

Statistics are usually represented with numerical figures, especially in scientific or technical writing:

We found that 7% of our study sample were not human.

This also applies to measurements:

We found that the blood sample of each alien subject contained, on average, 0.98 mg of Jupiter juice.

However, in formal, non-technical writing, these numbers and the accompanying measurements/symbols should be written out in full:

We spent ninety percent of the holiday on the beach.

Telephone Numbers

Telephone numbers should, of course, always be in numerals:

Report compiled by I. Amalien, head of Alien research at Melbourne University, telephone no. 05748 511784

Dates and Times

Dates should also be written numerically for the most part:

We first noticed that a significant proportion of the population of Australia could be of extra-terrestrial origin on 14 March 1985.

When talking about whole decades, you can write these out in words or numerals. If you choose numerals, however, remember to never put an apostrophe between the zero and the ‘s’:

The eighties were a tough time to get funding for alien research.

However, in the ’90s, we managed to secure a grant.

The most important thing here is consistency. Choose either use numerals or words and then stick to this throughout your document.

Times of day should be represented in numbers when ‘am’ or ‘pm’ are used:

We took the blood samples at 7am each morning.

However, if you use ‘o clock’, you should write the number in word form:

We administered the truth juice at nine o’clock each evening.