8 hours.
Nine and a half hours.
840
Nine hours.
4.5 hours
ten and a half
8:30am to noon is 3.5 hours.
It is (8.5 + 24k) hours where k is an integer.
8 hours and 30 minutes.
1960
14 + 24k where k is any integer.
There are 4 and 1/2 hours between 8:30 and 1.