How many hours is 3 hours, 40 minutes and 20 seconds,

How many hours is 3 hours, 40 minutes and 20 seconds,

3 + 40 / 60 + 20 / 3600 = 3 + 2 / 3 + 1 / 180 = (540 + 120 + 1) / 180 = 661 / 180 hours