Formula help with multiple tabs

Hi. New to forum. My spreadsheet has multiple tabs for different departments, say Departments 1-4. On a seperate tab I'll call "Summary" I want to be able to sum revenue from departments I select. In other words, if I want to see only department 1, then I could choose department 1 (say from a drop down box) and see the result. If I'd rather see how Departments 1 and 3 combine, then I want to be able to select departments 1 and 3 and see the result (multiple drop down boxes?). I want to select departments in any combination to see their results. So my questions are:

1) How do I set up the selection criteria? Multiple drop down boxes with Departments 1-4?
2) What formula do I use to sum the cells from different sheets based on my selection criteria?

I've attached a sample workbook to (hopefully) illustrate. Thanks in advance!!
Scott

Thanks. Unfortunately, the Total (row 15) doesnt' change when you select/deselect departments. The filter displays/hides the departments I want, but again, the total still sums all rows, regardless if they're hidden(selected) in the filter. Other thoughts?

Also, I want to be able to pull more than one metric (Revenue in my simple sample worksheet). For instance, I'll want to pull Revenue, Expenses, Net Income for the departments I select. I'm not sure using the filter as suggested would permit me do to so, unless I have multiple filters for each metric (not!).

Hi, It looks like them row should be expanded wider to show the full number.

Yes, the subtotal function with the filter works great for pulling one metric. Thanks! What I really need is to be able to select which department I want one time, then have it pull and sum several metrics (e.g. revenue, expenses, net income). I've uploaded the sample.xls with these updates. Thanks for your help!