How can you calcute how various hours one works per week or per sunshine ?

is it fact or fiction.How can you calcute how various hours one works per week or per sunshine ?
Take your total number of hours you worked for the week and divide it by the number of days you worked that week. For example I worked 40hr for 5 days. 40/5=8
I look at my time card.
In my mind, for a time if I work 8-5, I imagine a clock near a 12pm on it. 8-12 is 4 hours. 12-5 is 5 hours. Then I add 4+5 = 9.
wages * hourly * total amount of hour for the week. give you your total.
I don't know how to calcute.
Go through adjectives your time cards and convert minutes to 100ths of an hour. Add up all your clock-out times, and later all your clock-in times.
Subtract the total of the clock-in times from the total of the clock-out times to return with hours worked in hours and 100ths.
if you are worthy at MS Excel, it can calculate hours base on clock times..
Please tell me that this is not a serious interview