Numerals, Fractions and Dates

The compound numerals from twenty-one to ninety-nine are written with hyphens:

France is divided into ninety-six departments.

Mozart was only thirty-five years old when he died.

No additional hyphens are used in writing larger numbers:

A leap year has three hundred and sixty-six days.

The maximum possible score with three darts is one hundred and eighty.

In formal writing, the numerals from one to twenty are almost always written out:

The American flag has thirteen stripes.

We have four candidates for president.

Do not write:

*The American flag has 13 stripes.

*We have 4 candidates for president.

Larger numbers, however, may be written with digits:

The bomb killed 37 people and injured over 200 others.

Writing was invented less than 6000 years ago.

When writing a four-digit numeral in digits (other than a date), American writers never use a comma, but British writers usually do. Hence Americans write 2000 years and 3700 people, while Britons often write 2,000 years and 3,700 people. I consider such commas completely pointless, and I don't use them myself, but others may insist that you do so. A five-digit or larger numeral always takes one or more commas: 53,000 refugees, 170,000 cases of AIDS, 2,760,453 patents.

Naturally, we make an exception for addresses and other special cases, in which numerals are always written with digits:

I lived for years at 4 Howitt Road in Belsize Park.

Observe that it is bad style to start a sentence with a numeral: either the number should be written out, or the sentence should be rewritten:

*650 MPs sit in Parliament.

Six hundred and fifty MPs sit in Parliament.

There are 650 MPs in Parliament.

Fractions are always written with hyphens:

Almost three-fourths of the earth's surface is water.

More than one-half of babies born are male.

But note the following case:

One half of me wants to take the job while the other half doesn't.

Here the phrase one half is not really a fraction at all.

In formal writing, a fraction is always written out. You should not write things like the following:

*Almost ¾ of the earth's surface is water.

When we write a date, we usually put commas around the year:

It was on 18 April, 1775, that Paul Revere made his famous ride.

On December 7, 1941, the Japanese attacked Pearl Harbor.

She died on the last day of November, 1843.

In these days of minimal punctuation, however, many people now prefer to omit such commas:

It was on 18 April 1775 that Paul Revere made his famous ride.

On December 7 1941 the Japanese attacked Pearl Harbor.

She died on the last day of November 1843.

You may use either fashion, so long as you are consistent.

Important note: In British usage, a date is written day-month-year, while American usage prefers month-day-year. Hence, Britons write 23 March, while Americans write March 23. This is a potentially serious problem when we use the abbreviated style of writing dates often found in letters and business documents: to a Briton, 5/7/84 means 5 July, 1984, while to an American it means May 7, 1984. If you are writing something that might be read on the other side of the Atlantic, therefore, it is best to write out a date in full, to avoid any misunderstanding.

Maintained by the Department of Informatics, University of Sussex