How many hours is 8 PM to 630am?

ten and a half

8:00 pm to 00:00 midnight = 4:00 hours

00:00 to 6:30 am = 6:30 hours

total 10:30 = 4:00 + 6:30

or 10.5 hours

60 minutes = 1 hour

30 minutes = 1/2 hour = 0.5 hour