Listen to the vocabulary using the Jukebox, use the arrow on the right to go down or up into the list.

1. 20 (vingt) .21 (vingt et un).22 (vingt deux).23.24.25.26.27.28.29
2. 30 (trente).31 (trente et un).32.33.34.35.36.37.38.39
3. 40 (quarante).41 (quarante et un).42.43.44.45.46.47.48.49
4. 50 (cinquante).51 (cinquante et un).52.53.54.55.56.57.58.59
5. 60 (soixante).61 (soixante et un).62.63.64.65.66.67.68.69
6. 70. (soixante-dix) 71 (soixante et onze).72.73.74.75.76.77.78.79
7. 80 (quatre-vingt).81 (quatre-vingt un).82.83.84.85.86.87.88.89
8. 90 (quatre-vingt-dix) .91 (quatre-vingt onze).92.93.94.95.96.97.98.99

You can see that from 21 to 71 we use "and" "et" between the two numbers: "vingt ET un", "trente ET un", but for 81 and 91 no!
-70,80,90 are pretty complicated as you can see:
70 is 60 10, 80 is 4 20 and 90 is 4 20 10, other french speaking countries use septante for 70, huitante for 80 and nonante for 90 which are more logical (Switzerland, Belgium).

9. 100. 1000. 1,000,000 . 1,000,000,000

101: cent un
200: deux cents
1023: mille vingt trois
2000: deux mille (no s at the end)
1,000,000: un million
1,000,000,000: un milliard