Totals from worksheets on a totals sheet

The company I work for wants me to create a spreadsheet on some of the larger jobs I work on to keep track of quantities, part numbers, etc.
I will create the individual work sheets from the various areas with the quantities, part numbers, and descriptions.
What I would like to do is to make a "totals" sheet that lists the total quantity of the different part numbers, listing the part number only once.
I.E. I have a quantity of 3 pcs. of part number 123-456 on work sheet one(along with other parts), and I have 2 pcs. of part number 123-456 on work sheet two.
On my totals sheet, I would like to see a quantity of 5 pcs. for part number 123-456.
I have gone through the help and have not found anything that this easy enough for a little kid to do.
I have attached a small example of what I would like to accomplish.
Thank you so much for your help and suggestions.