Time is easier when you remember how many hours are in a day. in cell A1, enter your end time. In A2, your start time. Make sure that these are in time format. In A3, enter in =A1-A2, then format to number, 2 decimal places. In A4, enter in =A3*24 (for hours in a day)

For example (presuming formulas are entered, these are the answers
12:00 P
8:00 A
0.1
4.0

Hope this helps

Art