1.234 using 'one'

You use 'one' as a determiner when you have been talking or writing about a group of people or things and you want to say something about a particular member of the group. 'One' is used instead of 'a' or 'an' and is slightly more emphatic.

The use of 'one' as a number is explained in paragraphs 2.230 to 2.232.

1.235

Many determiners are also pronouns, that is they can be used without a following noun. For more information about these, see paragraphs 1.153 to 1.160.