You will need table related by item number with some simple calculated fields or a script to run the calc. Basically
DJ_1600H_Total = ItemTable::DJ_1600H * LineItemTable::Qty
You could do this with Calculated Global fields and merge fields/variables as well but it depends on how you want to use the data.
How do I do with calculated global fields?
I know about the global field but how do I make it calculated?