Editing numbers

Dates: How to write decades

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Shutterstock / svekloid / A tapestry of eight vintage patterns from the seventies featuring lots of oranges, yellows and browns. A banner through the middle reads ‘Patterns from the seventies, ’70s’.

Dates can cause a lot of issues in scientific writing. Here we will focus on just one aspect of writing dates: decades.

Decades

Decades can be spelled out or expressed as numerals.

• the nineties (spelled out)

• the 1990s (numerals)

Apostrophes in decades

There is no apostrophe between the number and the ‘s’ in the numeral form of a decade.

• the 1880s (not 1880’s)

• the 1920s (not 1920’s)

This is because the decade is being expressed as a plural, not a possessive.

Shortened decades

Shortened decades are contractions. They require an apostrophe before the number to indicate there are numbers missing. But be careful, as the contraction needs a closing apostrophe, not an opening apostrophe.

• the ’90s

• the ’70s

Resources

Most style guides have a section on decades, including Section 9.33 of The Chicago Manual of Style (CMOS), and the Australian Government Style Manual.