Il numero 31, trentuno in Italiano, in Inglese si dice thirty-one.
Il numero ordinale 31° in inglese si dice thirty-first.
22: twenty-two 23: twenty-three 24: twenty-four 25: twenty-five 26: twenty-six 27: twenty-seven 28: twenty-eight 29: twenty-nine 30: thirty 32: thirty-two 33: thirty-three 34: thirty-four 35: thirty-five 36: thirty-six 37: thirty-seven 38: thirty-eight 39: thirty-nine 40: forty