Large numbers – cent, mille, million

Cent (100)

• 100 cent, 101 cent un, 150 cent cinquante
• 200 deux cents, 300 trois cents
• 210 deux cent dix

Cent takes an s when it's multiplied and nothing follows: deux cents, but deux cent trois. No un before cent: un cent.

Mille (1,000)

• 1 000 mille, 2 000 deux mille, 10 000 dix mille
• 1 999 mille neuf cent quatre-vingt-dix-neuf

Mille never takes an s and has no un before it.

Years

• 1789 mille sept cent quatre-vingt-neuf (or dix-sept cent quatre-vingt-neuf)
• 2025 deux mille vingt-cinq

Million and milliard

Million (million) and milliard (billion) are nouns: they take an s in the plural and need de before a noun:

• un million d'habitantsa million inhabitants
• trois millions d'eurosthree million euros
• deux milliards de personnestwo billion people

Writing numbers

French uses a space (or a dot) for thousands and a comma for decimals, the opposite of English:

• 1 250 0001,250,000
• 3,5 %3.5%
• 12,99 €€12.99 (said douze euros quatre-vingt-dix-neuf)

Approximate numbers

• une centaine de personnesabout a hundred people
• des milliers de touristesthousands of tourists

See Fractions, percentages and approximate numbers.