Silvia M. answered 05/26/19
Kind and effective tutor for Italian (from basic to advanced)
Hi, the expression "un terzo d'ora" is not used. Only "mezz'ora", "un quarto d'ora", un'ora e mezzo", "un'ora e un quarto" etc... For every amount of time that is not half or a quarter it is necessary to mention the number of minutes. So "un terzo d'ora" can only be expressed as "venti minuti".