If you are talking about from 12pm-4pm = 4 hours. If you are talking about from 12am-4pm = 16 hours.
9am, 10am, 11am, 12pm, 1pm, 2pm, 3pm, 4pm, 5pm. 8 hours.
12am to 4pm is 16 hours.
6 hours from 4pm to 10pm
12pm to 7pm is a span of 7 hours.
7am to 4pm is 9 hours.
3 hours between 12pm and 3pm
4pm to midnight is 8 hours.
21
10am to 4pm is a period of six hours.
12 hours
6 hours.