A B C
D
Part number Qty Received Qty Shipped Balance

I have a spreadsheet with the above columns. I want to enter a qty. in
column B row* and it will add (update) the qty in coorespnding row cell in
column D. I also want to enter a value in a single cell in column c that will
subtract that value from all the cells in column D.

When entering a new value in cell C, the previous values entered shall be
retained in column D and will only be affected by the current entry. THANKS