• 3-minute read
• 28th December 2015

One, 2, III: Using Numbers in Academic Writing

No matter what you’re studying, at some point in your academic career you’ll find yourself using numbers in your written work.

This might not seem too problematic, but there are important differences between using numbers in formal academic writing and in everyday life.

Numerals or Words?

The biggest question when it comes to numbers in academic writing is whether to use numerals (1, 2, 3, 4, etc.) or words (one, two, three, four, etc.). The general guideline is to write smaller numbers up to ten as words, with numerals saved for larger numbers.

Annoyingly, there is no consensus on this. For instance, the APA Style Guide recommends using numerals for ten and up (or “10 and up,” if we’re doing this the APA way). But the Chicago Manual of Style suggests spelling out all numbers up to one hundred.

The important thing is to check your school’s style guide and use a consistent system throughout each paper you write.

Roman Numerals

You may also need to understand Roman numerals. These aren’t so common these days, but you do see them in things like copyright dates (MCMLXXXVI = 1986) and the names of monarchs (Queen Elizabeth II).

Big Numbers

Despite the above rule, some bigger numbers are expressed either as words or as a combination of words and figures. For example, it is to say:

The Earth is 4.542 billion years old.

But writing this out in numerals is a bit confusing, as there are many zeroes:

The Earth is 4,542,000,000 years old.

Commas and Hyphens

Punctuating numbers correctly is also important. When expressing a number over one thousand, for example, it’s common to separate the thousands with a comma:

One thousand = 1,000

One hundred thousand = 100,000

One million = 1,000,000

Hyphens, meanwhile, should be used either when expressing a number with more than one word (e.g., twenty-two) or when as part of an adjectival phrase modifying a noun (e.g., “I’m holding a seven-year-old grudge”).

Dates, Years and Centuries

Dates (e.g., 06/12/2013 or 6 December 2013) and years (e.g., 1948, 300-250 BCE) are usually written using numerals. Centuries, however, should be written out in full (i.e., “eighteenth century” rather than “18^th century”).

Technical Numbers

In technical writing, such as in the sciences and math, it’s more common to use numerals than words. This is especially true when a number is followed by a unit of measurement. So, for instance, the weight “four grams” could be expressed as “4 g” or “4 grams.”