Q: I want to use SAPgui to find the check number used to pay an invoice.

Answer

The easiest way to find a check number associated with a particular PO is to use Atlas and look at the invoice/payment history.
If you prefer to use the SAPgui, the procedure is as follows:

1. Display the PO.
2. In the Item Overview, select all of the line items.
3. From the menu choose Item > Statistics > PO History.
4. Double-click on the invoice document number
   Result: The "Display: Document Overview" window appears.
5. In the Items in Document Currency list,double-click on the first item.
   Result: The "Display Document: Line Item 001" window appears.
6. From the menu choose Environment > check information to display the check information.

If there are multiple invoices, repeat steps 4-6 for each invoice.