11 Numbers and dates

11.1 Numbers: general principles

11.1.1 Introduction

This chapter mainly covers general texts and the humanities; more detailed information about dealing with numbers in scientific contexts can be found in Chapter 14, particularly 14.1, and 14.6.1 discusses typography in mathematical notation.

11.1.2 Figures or words?

The main stylistic choice to be made when dealing with numbers is whether to express them in figures or in words. It is normal to determine a threshold below which numbers are expressed in words and above which figures are used; depending on the context, the threshold may vary. In non-technical contexts, Oxford style is to use words for numbers below 100; in technical contexts numbers up to and including ten are spelled out. In specialist contexts the threshold may, with good reason, be different: in some books about music, for example, numbers up to and including twelve are spelled out (there being twelve notes in the diatonic scale). The threshold provides only a general rule: there are many exceptions to it, as described below. On websites different rules may apply: figures tend to be used more than words.

Large round numbers may be expressed in a mixture of numerals and words (6 million; 1.5 million) or entirely in words (six million; one and a half million). In some contexts it makes better sense to use a rounded number than an exact one, such as a population of 60,000 rather than of 60,011. This is particularly true if the idea of approximation or estimation is expressed in the sentence by such words as some, estimated, or about. Rounded approximations may be better expressed in words if the use of figures will confer a false sense of exactitude:

about a thousand not about 1000
some four hundred not some 400

Particularly where quantities are converted from imperial to metric (or vice versa), beware of qualifying a precise number with about, approximately, etc.: about three kilometres should not be converted to about 1⅞ miles.

In expressing approximate figures some styles traditionally preferred more than to over. Modern usage tends to treat them as synonyms:

She was born in Oxford and has lived in Ireland for over twenty-five years
She was born in Oxford and has lived in Ireland for more than twenty-five years

although there are certain contexts in which one or the other is syntactically correct:

We spent a lot of time together, well over two months, and so we really got to know each other
There’s more than one way of tackling this problem

or sounds more natural, e.g. in reference to age:

Applicants must be over 25 and have had a clean driving licence for more than five years

Use words in informal phrases that do not refer to exact numbers:

talking nineteen to the dozen
I have said so a hundred times
she’s a great woman—one in a million
a thousand and one odds and ends

When a sentence contains one or more figures of 100 or above, a more consistent look may be achieved by using Arabic numerals throughout that sentence: for example, 90 to 100 (not ninety to 100) and 30, 76, and 105 (not thirty, seventy-six, and 105). This convention holds only for the sentence where this combination of numbers occurs: it does not influence usage elsewhere in the text unless a similar situation exists.

In some contexts a different approach is necessary. For example, it is sometimes clearer when two sets of figures are mixed to use words for one and figures for the other, as in thirty 10-page pamphlets or nine 6-room flats. This is especially useful when the two sets run throughout a sustained expanse of text (as in comparing quantities):

the manuscript comprises thirty-five folios with 22 lines of writing, twenty with 21 lines, and twenty-two with 20 lines
Anything more complicated, or involving more than two sets of quantities, will probably be clearer if presented in a table.

Spell out ordinal numbers—first, second, third, fourth—except when quoting from another source. In the interests of saving space they may also be expressed in numerals in notes and references (see also 11.6.2 below). Use words for ordinal numbers in names, and for numerical street names (apart from avenue names in Manhattan—see 6.2.4):

the Third Reich

the Fourth Estate

a fifth columnist

Sixth Avenue

a Seventh-Day Adventist

It is customary to use words for numbers that fall at the beginnings of sentences:

Eighty-four different kinds of birds breed in the Pine Barrens
‘How much?’ ‘Fifty cents’

In such contexts, to avoid spelling out cumbersome numbers, recast the sentence, writing for example The year 1849 … instead of Eighteen forty-nine …

Use figures for ages expressed in cardinal numbers, and words for ages expressed as ordinal numbers or decades:

a girl of 15

a 33-year-old man

between her teens and twenties

in his thirty-third year

in the twenty-first century

In less formal or more discursive contexts (especially in fiction), ages may instead be spelled out, as may physical attributes:

a two-year-old

a nine-inch nail

Words can supplement or supersede figures in legal or official documents, where absolute clarity is required:

the sum of nine hundred and forty-three pounds sterling (£943)
a distance of no less than two hundred (200) yards from the plaintiff

Figures are used for:

  • • parts of books, including chapters, pages, and plates (p. 14, Chapter 7)

  • • numbers of periodicals (Language 61)

  • • scores of games and sporting events (a 3–1 defeat, 37 not out)

  • • distances of races (the 400 metres)

  • • house or building numbers (47 Marston Street)

  • • road or highway numbers in a national system (A40, M25, Route 66).

11.1.3 Punctuation

When written in words, compound numbers are hyphenated (see 11.1.6 for fractions):

ninety-nine

one hundred and forty-three

in her hundred-and-first year

In non-technical contexts commas are generally used in numbers of four figures or more:

1,863

12,456

1,461,523

In technical and foreign-language work use a thin space (see 14.1.3):

14 785 652

1 000 000

3.141 592

In tabular matter, numbers of only four figures have no thin space, except where necessary to help alignment with numbers of five or more figures.

There are no commas in years (with the exception of long dates such as 10,000 bc), page numbers, column or line numbers in poetry, mathematical workings, house or hotel-room numbers, or in library call or shelf numbers:

1979

1342 Madison Avenue

Bodl. MS Rawl. D1054

BL, Add. MS 33746

11.1.4 Number ranges

Numbers at either end of a range are linked with an en rule. A span of numbers is often elided to the fewest figures possible:

30–1

42–3

132–6

1841–5

but retain as many digits as necessary where they change across the range:

65–71

352–62

1491–560

89,999–90,000

In any event, do not elide digits in (or ending with) the group 10 to 19 because of the way they are read or spoken:

10–12

15–19

114–18

310–11

However, some editorial styles vary greatly in their treatment: for example some require no elision, some elide to the final two digits, and some don’t elide multiples of 10 or 100 (30–32; 100–101).

Even in elided styles all digits may be preserved in more formal contexts, such as titles and headings, and in expressing people’s vital dates:

Charles Dickens (1812–1870)
The National Service of British Seamen, 1914–1918
Turbulent years, 1763–1770

Dates that cross the boundary of a century should not be elided: write 1798–1810, 1992–2001. Spans in bc always appear in full, because an elided second date could be misread as a complete year: 185–22 bc is a century longer than 185–122 bc, and dates for, say, Horace (65–8 bc) might appear to the unwary to express a period of three rather than fifty-seven years.

When referring to events known to have occurred between two dates, historians often employ a multiplication symbol: 1225 × 1232 (or in some styles 1225 × 32) means ‘no earlier than 1225 and no later than 1232’. The multiplication sign is also useful where one element in a range is itself a range: 1225 × 32–1278.

In specifying a range use either the formula from xxxx to xxxx or xxxx–xxxx; take care to avoid the mistake of combining the two. It is the war from 1939 to 1945 or the 1939–45 war, never the war from 1939–45. The same applies to the construction ‘between … and …’: the period between 1998 and 2001 or the period 1998–2001, but not the period between 1998–2001. For ranges that include a negative value, it is best to use words to avoid confusion between a negative number and a dash, or to prevent an en rule clashing with a minus sign: 95% confidence interval = -743.23 to -557.28 not 95% CI = -743.23 – -557.28.

When describing a range in figures, repeat the quantity as necessary to avoid ambiguity:

1000–2000 litres

1 billion to 2 billion light years away

The elision 1–2000 litres means that the amount starts at only 1 litre, and 1 to 2 billion light years away means that the distance begins only 1 light year away.

For ranges that include a unit, the unit symbol does not need to be repeated (45.650.2 kg) unless the symbol is normally closed up (14°–18° [of angle])

A solidus replaces the en rule for a period of one year reckoned in a format other than the normal calendar extent: 49/8 bc, the tax year 1934/5. A span of years in this style is joined by an en rule as normal: 1992/3–2001/2.

Use a comma to separate successive references to individual page numbers: 6, 7, 8; use an en rule to connect the numbers if the subject is continuous from one page to another: 6–8.

11.1.5 Singular or plural?

Whether they are written as words or figures, numbers are pluralized without an apostrophe (see also 4.2.2):

the 1960s

the temperature was in the 20s

they arrived in twos and threes

she died in her nineties

Plural phrases take plural verbs where the elements enumerated are considered severally:

Ten miles of path are being repaved
Around 5,000 people are expected to attend

Plural numbers considered as single units take singular verbs:

Ten miles of path is a lot to repave
More than 5,000 people is a large attendance

When used as the subject of a quantity, words like number, percentage, and proportion are singular with a definite article and plural with an indefinite:

The percentage of people owning a mobile phone is higher in Europe
A proportion of pupils are inevitably deemed to have done badly

None in the sense no one person takes the singular:

Later, 26 children and one teacher went to hospital, but none was seriously injured

but in the sense of not any takes the plural verb:

He had hoped to receive parking permits for residents but none were forthcoming

The numerals hundred, thousand, million, billion, trillion, etc. are singular unless they refer to indefinite quantities:

two dozen

about three hundred

some four thousand

more than five million

but

dozens of friends

hundreds of times

thousands of petals

millions of stars

Note that a billion is a thousand million (1,000,000,000 or 109), and a trillion is a million million (1012). In Britain a billion was formerly a million million (1012) and a trillion a million million million (1018); in France, Germany, and elsewhere these values are still used.

11.1.6 Fractions and decimals

Fractions in mathematical contexts are discussed in 14.6.6. In other material, spell out simple fractions in running text. When fractions are spelled out they are traditionally hyphenated:

two-thirds of the country

one and three-quarters

one and a half

although they are increasingly written as open compounds (three quarters).

Hyphenate compounded numerals in compound fractions such as nine thirty-seconds of an inch; the numerator and denominator are hyphenated unless either already contains a hyphen. Do not use a hyphen between a whole number and a fraction: one and seven-eighths rather than one-and-seven-eighths. Combinations such as half a mile and half a dozen should not be hyphenated, but write a half-mile and a half-dozen.

In statistical matter use specially designed fractions where available (½, ¾, etc.), which have a diagonal bar—the Unicode block ‘Number Forms’ has a range of single-character fractions. The form of fraction with a horizontal bar (e.g. ) is satisfactory—even in running text—if presented in TeX, which subtly adjusts interline spacing and character size and spacing, but if not set in TeX, seldom looks elegant. In non-technical running text, set complex fractions in text-size numerals with a solidus between (19/100).

Decimal fractions may also be used: 12.66 rather than 12⅔, 99.9 rather than 99 and 9/10. Decimal fractions are always printed in figures. They cannot be plural, or take a plural verb. For values below one the decimal is preceded by a zero: 0.76 rather than .76. Exceptions are quantities (such as probabilities) that never exceed one, although authorities differ on this; if house style does not specify, it is best to follow the author’s notation.

Decimals are punctuated with the full point on the line. In the UK decimal currency was formerly treated differently, with the decimal point set in medial position (£24·72), but this style has long been out of favour.

Note that European languages, and International Standards Organization (ISO) publications in English, use a comma to denote a decimal sign, so that 2.3 becomes 2,3.

For the use of decimals in tables see Chapter 15.


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