Use the following rule to name ordinal numbers from one to ten:
1-first, 2-second, 3-third; any ordinal number not ending in 1, 2 or 3 should end in "th."
The rule applies to numbers ending in one to zero. For example, twenty-first (21st), thirty-third (33rd), eighty-second (82nd), nineteenth (19th), sixty-fourth (64th), ninety-fifth (95th).
Say "th" after the number if the ten's digit of the number is 1. For example, 2,413 becomes two thousand four hundred thirteenth (2413th). Another example is 14, which becomes "fourteenth," or "14th."
Say the cardinal number followed by an ordinal number when referring to ordinal numbers higher than 20 that do not end in zero, such as 21st (twenty-first) or 76th (seventy-sixth).