I'm new to the community here so bare with me if my lingo isn't up to par
just yet. I'm in Excel 2003.
My workbook has 2 sheets; 'Inventory' and 'Source'.

'Inventory' has:
Month     SKU#      Beginning Inventory      Ending Inventory
Jan '08    555              50,000                    
             444              35,000        
             333              40,000

'Source' has:
Order Date       SKU#    Quantity
01/13/08          555         25,000
01/22/08          444         10,000
01/22/08          444         3,000
01/22/08          333         5,000
01/31/2008       555         3,000
02/13/08          555         2,000
02/22/08          333         1,500

I'm needing to provide the 'Ending Inventory' to the "Inventory" worksheet,
using the beginning quantity (in 'Inventory'), subtracting the total quantity
for each month (In 'Source'), by SKU #.

In my terms, the Ending Inventory for Jan '08, for SKU # 555 above would be:
Beginning Inventory shows 50,000
If SKU = 555 & Date is between 01/01/2008:01/31/2008 = 28,000
If SKU = 444 & Date is between 01/01/2008:01/31/2008 = 13,000

It's the 'between this date range' that is throwing me off and then coupling
it with the SKU #s.

Any direction is much appreciated.  Truly!
thnx!