Highlight the area you want to run, click on Data - then Subtotals. You can subtotal by any of the multiple columns you have, in this case it sounds like individual departments or employee names. Check the individual columns you want to total (such as hours worked) and check the subtotals on bottom box and you can have a total all of these hours.
You can also use the subtotals formula to run the same 9 different functions including adding, averaging, counting, etc...
Good luck
