match debits with credits
 

In my previous posts I was asking about counting unique invoice
numbers and Purchase Order numbers (PO's). Well, now I have a new
problem. I have to go through and evaluate the invoice numbers and
po's and eliminate any matching debits and credits from my count. This
may or may not affect including an invoice and po in my count. Many
invoices can be included on one po. What type of formula do I use to
match the debits and credits of an invoice number?

MILTENYI BIOTEC INC 16-Aug-07 PO 0721868 778184 $455.00
MILTENYI BIOTEC INC 16-Aug-07 PO 0721868 778184 ($492.00)
MILTENYI BIOTEC INC 16-Aug-07 PO 0721868 778184 $455.00
MILTENYI BIOTEC INC 16-Aug-07 PO 0721868 778184 $492.00
MILTENYI BIOTEC INC 16-Aug-07 PO 0721868 $37.00
MILTENYI BIOTEC INC 16-Aug-07 PO 0721868 778184 ($455.00)

MILTENYI BIOTEC INC 16-Aug-07 PO 0721963 777976 ($550.00)
MILTENYI BIOTEC INC 16-Aug-07 PO 0721963 $37.00
MILTENYI BIOTEC INC 16-Aug-07 PO 0721963 777976 $500.00
MILTENYI BIOTEC INC 16-Aug-07 PO 0721963 777976 $550.00
MILTENYI BIOTEC INC 21-Aug-07 PO 0722270 $37.00
MILTENYI BIOTEC INC 21-Aug-07 PO 0722270 778660 $520.00
MILTENYI BIOTEC INC 21-Aug-07 PO 0722271 $62.00
MILTENYI BIOTEC INC 21-Aug-07 PO 0722271 779439 $530.00