adding up totals of various documents or sheets
i've made an invoice document, simlilar to the invoice template that comes with numbers 08.
i duplicate an old invoice to write a new one (i could also just duplicate the sheet, so all invoices are in the same document, if that makes it easier).
now i want a document (or a sheet within an document that contains all invoices) that lists all the sums of the invoices and adds them up. i want a total of all the invoices i create, a total that *automatically updates* when i create a new invoice by duplicating an older invoice.
thanks.
Powermac G5 / 12" Powerbook, Mac OS X (10.5.6)