Il numero 30, trenta in Italiano, in Inglese si dice thirty.
Il numero ordinale 30° in inglese si dice thirtieth.
21: twenty-one
22: twenty-two
23: twenty-three
24: twenty-four
25: twenty-five
26: twenty-six
27: twenty-seven
28: twenty-eight
29: twenty-nine
31: thirty-one
32: thirty-two
33: thirty-three
34: thirty-four
35: thirty-five
36: thirty-six
37: thirty-seven
38: thirty-eight
39: thirty-nine