Carol,
I'm assuming that one worksheet is for Goods In, and the other is for Goods
Out.

Goods In Worksheet
Date Store Part# Qty In
01/03/2010 A 1 20
01/03/2010 B 1 10
01/03/2010 A 2 30
01/03/2010 A 2 0

Parts total at stock take.

Goods Out worksheet
Date Part# Qty Out Store Tech ID
02/03/2010 1 5 A Harry
02/03/2010 1 20 B Fred


Main Worksheet
Part# Stock
1 5
2 30
3

Stock calculated with the following formula in B2 and copied down.

=SUMPRODUCT(--(GoodsIn!C:C=Main!A2),(GoodsIn!D:D))-SUMPRODUCT(--(GoodsOut!B:B=Main!A2),(GoodsOut!C:C))

Main is the sheet1 name.

HTH
Peter


"Carol" wrote:

I have a workbook with 3 worksheets, 1 main (total inventory), 2 sub
worksheets.
One of the sub worksheets tracks part #, store # and qty out, the other one
tracks part #, qty out, store # and tech id. I want to be able to insert
into the sub sheets and the main sheet have the items deducted.
Each day I physically enter new entries into the sub sheets, then re-enter
into the main sheet so the main sheet will show a true inventory.
Is there a way around all the duplicate entries?