2.231 'one'

'One' is used as a number in front of a noun to emphasize that there is only one thing, to show that you are being precise, or to contrast one thing with another.

• That is the one big reservation I've got.
• He balanced himself on one foot.
• There was only one gate into the palace.
• This treaty was signed one year after the Suez Crisis.
• It was negative in one respect but positive in another.

'One' can also be used, like other numbers, as a quantifier.

• One of my students sold me her ticket.
• ...one of the few great novels of the century.
• I was one of the most experienced organisers on campus.

'One' also has special uses as a determiner and a pronoun. These are explained in paragraph 1.234 and paragraphs 1.157 to 1.160.

2.232

When a large number begins with the figure '1', the '1' can be said or written as 'a' or 'one'. 'One' is more formal.

• ...a million dollars.
• ...a hundred and fifty miles.
• Over one million pounds has been raised.