Quantities on Invoice

We need to have "quantities sold" appear on invoices.  For example, if 750sf is sold to a customer, the invoice should show how many boxes that amounts to.  Same for carpet, if 750 sf of carpet is sold, the invoice should show 12 x 62'6".  This information, along with the ROLL #, is very important for stocking stores.  It would be very time saving to have this information provided on invoices.