Listen to the jukebox. Ordinal in Spanish.

1. Primero / first - 1st
2. Segundo / Second - 2nd
3. Tercero / Third - 3rd
4. Quatro / Fourth - 4th
5. Quinto / Fifth - 5th
6. Sexto / Sixth - 6th
7. Séptimo / Seventh - 7th
8. Octavo / Eight - 8th
9. Noveno / Ninth - 9th
10. Décimo / Tenth - 10th
11. Undécimo / Eleventh
12. Duodécimo / 12th
13. Decimotercero / 13th
14. Vigésimo / 20th
15. Vigésimo primero / 21th
16. Trigésimo / 30th

All these words have a feminine form wich ends with a "a": primera, segunda...
Primero, Tercero, Decimotercero drop the final "o" before a masculine singular word: el primer hombre.

After 11th, the ordinal numbers in Spanish are not really used, for example, instead of saying "el siglo vigésimo primero" (the 21st century), we say "el siglo veintiuno".