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

1. Premier / 1st
2. Première (f) / 1st
3. Deuxième / 2nd (when you have more than 2 things)
4. Second / 2nd (when you only have two things)
5. Troisième / 3rd
6. Quatrième / 4th
7. Cinquième / 5th
8. Sixième / 6th
9. Septième / 7th
10. Huitième / 8th
11. Neuvième / 9th
12. Dixième / 10th
13. Vingt et unième / 21st
14. moitié (f) / 1/2
15. tiers (m) / 1/3
16. quart (m) / 1/4
17. cinquième (m) / 1/5
18. nième or n-ième or enième / nth

We use the word first or "premier" about the first day of the months, we say "le premier juin", but after we say "le deux juin"...
For "second", you can hear that the letter "c" is pronounced like a "g" . A "s" between 2 vowels is like a "z" (troisième). The "x" of sixième is a "z".
For half we have "moitiè" and also "demi" we use to give the time.

So now, you understand the rule: you drop the final "e" when there is one and you add -ième, you can also see that 5th and 1/5 are the same word, the same for 6th and 1/6...