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1.35 Numbers and abbreviations in writing


1 Ten or 10?

1 – 10 are usually best written as full words (one, two , three etc). 11+ would be written as numbers. There’s no strict rule on this: 11-20 may often also be written as words, but 21+ would almost always be put down as numbers. Make sure you’re consistent over this: don’t sometimes write twenty but in other places 20.

2 Figures, table, section, chapter numbers

Figure and table numbers and sections should be written as numbers: Figure 6.3; Table 4.2 etc.

Chapters numbers can be written as numbers or words, but again, be consistent.

3 Page numbers

Page numbers are usually on the right hand side, top or bottom.

4 Money

The pound sign comes before the figure: £3.99, £100 etc. The same goes for dollars and euros. Always make clear what currency you’re referring to.

Millions are often abbreviated to m. £3m = 3 million pounds. $6.7m = 6.7 million dollars.

You may see thousands abbreviated to k, often when talking about salaries. A salary of £35k is £35,000 pounds a year.

5 Large numbers

1,000/1000 = a thousand
10,000 = ten thousand
100,000 = one hundred thousand
1,000,000 = a million
10,000,000 = ten million
100,000,000 = one hundred million
1,000,000,000 = a billion (one thousand million)
(In the UK, a billion used to be a million million, and some
people may still interpret it as such).

6 Singular forms with plural meanings

After a number, dozen, hundred, thousand, million and billion do not add –s, and of is not used.

six hundred people (but, hundreds of people)
two thousand cities (but, thousands of cities)
nine million years (but, millions of years)

Singulars are also used as modifiers before nouns in plural expressions of measurement:

a twenty- pound note
a two- hour exam
a ten-kilometre walk

When using the old non-metric system to talk about height and weight, foot and stone often remain singular, particularly in more informal English:

I’m five foot ten inches tall
I weigh twelve stone six pounds

7 Decimals

We normally write decimals with a period (full stop), not a comma:

0.75 (nought point seven five)

6.4 (six point four)

3.059 (three point oh five nine)

A comma is used to separate thousands (see above).

8 Percentages

A percentage is considered as a plural:

60% of the replies were invalid.

9 Roman numerals

Although very rare in everyday life, Roman numerals are still fairly common in books and academic writing in general. They may be used for the first few pages of a long piece of work before the main body (Abstract, Acknowledgements etc), to number a list, for the names of kings and queens (Henry VIII, Elizabeth II), and sometimes for names of centuries (a XVII century invention). The BBC puts the year of copyright of its programmes in Roman numerals. Only use them if you’re very familiar with them: it’s not worth trying to use them for the sake of it.

10 Years

Years are never written with a comma: 1999, 2003 etc.

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1 Full stops

Full stops are not usually used with abbreviations nowadays. (They used to be, so you still might see it). So, just write:

Mr Popp
Doolittle & Dalley Ltd
20 kg

The same is true when the abbreviation is formed by the first letters of several words:

the BBC
the EU

2 Capital letters

Abbreviations such as UNESCO are usually written in capital letters. Recently, however, some of these (often referred to as acronyms) are being written just with a capital first letter:

the Aids epidemic

If you’re not sure, use capitals.

3 Etc etc

There are certain abbreviations which are commonly found in academic writing. Here is a list with meanings. Some may be considered a little informal; for example, etc, eg (write for example), ie (write that is):

NB “note well”: used before important information to highlight it

viz. used to introduce a list of specific items or examples = namely

op. cit . used in referencing, to refer to a source already mentioned

loc.cit. in the place cited

ibid used in referencing, to show that a source is the same as the one immediately preceding it

c. or ca approximately (c.1650)

cf. compare

et al. “and the others”; used for in-text references when there are more than three authors

Q.E.D “which was to be shown”

4 Style

Apart from the examples above, and maybe some others connected to your specialist subject, you should not use abbreviations in your more formal writing.

Never use contractions (it’s, they’ll etc). Always write the full form.

Never use colloquial abbreviations such as uni, B’ham, info.

If you need to refer often to an organisation or a specialist term with a long name, for example Bovine Spongiform Encephalopathy or the National Society for the Prevention of Cruelty to Children , when you first make a reference you would normally put the name in full with the abbreviated form in brackets,and then subsequently just put the abbreviation.

Links to further resources on numbers and abbreviations

Sussex University



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Steve Gould
Last updated: 4 January 2011

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