1 one first
2 two second
3 three third
4 four fourth
5 five fifth
6 six sixth
7 seven seventh
8 eight eighth
9 nine nineth
10 ten tenth
11 eleven eleventh
12 twelve twelfth
13 thirteen thirteenth
14 fourteen fourteenth
以此类推.
20 twenty twentieth
21 twenty-one twenty-first
22 twenty-two twenty-second