Did you know that we have 2 different words to say “one and a half” in Russian? The first one is полтора, which is used with masculine and neuter nouns, ans the second one, полторы, which is used with feminine nouns. Please, note that Genitive singular is used after these numerals.
Я работал полтора часа. I have been working for one hour and a half.
Через полторы недели у меня будет отпуск! I will be on holidays in one week and a half.