Il numero 15, quindici in Italiano, in Inglese si dice fifteen.
Il numero ordinale 15° in inglese si dice fifteenth.
6: six 7: seven 8: eight 9: nine 10: ten 11: eleven 12: twelve 13: thirteen 14: fourteen 16: sixteen 17: seventeen 18: eighteen 19: nineteen 20: twenty 21: twenty-one 22: twenty-two 23: twenty-three 24: twenty-four