I. Numbers

1. Hyphens connect the components of compound numbers from 17 to 99.

dix-sept, quatre-vingt-dix-sept.

Exception. Et replaces the hyphen in 21, 31, 41, 51, 61, and 71.

vingt et un, soixante et onze.

2. Cent and vingt ^ add -s, when preceded by a multiplying numéral, and not followed by a numéral.

quatre-vingts, but quatre-vingt-trois ; deux cents, but deux cent vingt.