Answer:
From 1st to 10th
1st -> Primero
2nd -> Segundo
3rd -> Tercero
4th -> Cuarto
5th -> Quinto
6th -> Sexto
7th -> Séptimo
8th -> Octavo
9th -> Noveno
10th -> Décimo
From 10th to 19th
Rule: decimo+ordinals (1-10)
For example:
11th -> Décimoprimero /Décimo primero or Undécimo (another valid way to say it)
12th -> Décimosegundo / Décimo segundo
13th -> Décimotercero / Décimo tercero
However 18th-> Décimoctavo / Décimo octavo not "Décimooctavo"
and so on...
From 20th to 90th
20th -> vigésimo
- 21st -> vigésimo primero
- 22nd -> vigésimo segundo
- and so on...
30th -> trigésimo
- 31st -> trigésimo primero
- 32nd -> trigésimo segundo
- and so on... (including the following ones)
40th -> cuadragésimo
50th -> quincuagésimo (that's hard to pronunce, even for me haha)
60th -> sexagésimo
70th -> septuagésimo
80th -> octogésimo
90th -> nonagésimo
100th
100th -> centésimo
200th to 900th
Rather rare. Instead of saying the theoretically correct form, Spanish speakers in informal speech use a shortcut, instead of saying El ciclista fue el ducentésimo. (The cyclist was the 200th), it is common to hear El ciclista quedó en el lugar [número] doscientos (200). (The cyclist "got" the place [number] 200). "Doscientos" is the cardinal 200.
1,000th
1,000th -> Milésimo
Step-by-step explanation:
Native Speaker here, I hope that this is helpful to you!