English: ordinal numbers

-st is used with numbers ending in 1 (e.g. 1st, pronounced first)
-nd is used with numbers ending in 2 (e.g. 92nd, pronounced ninety-second)
-rd is used with numbers ending in 3 (e.g. 33rd, pronounced thirty-third)
As an exception to the above rules, all the "teen" numbers ending with 11, 12 or 13 use -th (e.g. 11th, pronounced eleventh, 112th, pronounced one hundred [and] twelfth)
-th is used for all other numbers (e.g. 9th, pronounced ninth).

English