Check-digit printing means

摘要

The invention contemplates a document printer for the automatically indexed sequential account numbering of successive documents, with the added feature of printing alongside each sequential number an automatic indication of the validity or invalidity of the number printed, said indication being a "check digit" which, in conjunction with the printed account number, renders the printed account number self-checking. The invention is described in application to weighted-modulus self-checking systems of the Modulus 10 and Modulus 11 varieties, inter alia.