There are 16 hours from 9 PM to 1 PM the next day.
(8.5+24k) hours where k is an integer.
5 and 1/2
12 hours
12 hours
12 Hours ! There are 12 hours in the AM and 12 hours in the PM !
From midnight (am) to Noon (pm) is 12 hours.
2.5 hours
21 hours
2 hours
3 hours
7 and a half hours