1 Un chiffre is the sign that is used to express a number (un nombre). 57 is un chiffre. Cinquante-sept is un nombre. The number (le nombre) 535 is written with chiffres 5, 3, and 5. Le numéro is used to refer to a specific number, such as a street number, a room number. L’immeuble numéro (n°) 14. Il habite au numéro 45.
2 Note that in numbers 21, 31, 41, 51, 61, 71 the conjunction et is used; there is no hyphen: vingt et un. Et is not used in 81, 91, 101; a hyphen is used in 81 and 91: quatre-vingt-un, quatre-vingt-onze, cent un.
3 When vingt and cent are multiplied, they become plural.
4 When vingt and cent are followed by another number, they are singular.
5 Mil is only used in dates. Mille is used in all other instances as well as in dates.
6 Million is preceded by the indefinite article: un million de touristes. Note that un million is like a noun of quantity and takes de before the following noun: un million d’hommes. In France and Quebec a comma is used in place of the decimal point used with numbers in the United States and English Canada. Instead of a comma used with numbers in the United States and English Canada, a period or a space is used in France and a space is used in Quebec. In France, it is becoming more common to use a space instead of a period.
7 Second is usually used when there are only two in a series.
