>>SOURCE FORMAT IS FREE
IDENTIFICATION DIVISION.
   PROGRAM-ID. UPC-CHECK.
ENVIRONMENT DIVISION.
   CONFIGURATION SECTION.
      REPOSITORY.
         FUNCTION ALL INTRINSIC.
DATA DIVISION.
   WORKING-STORAGE SECTION.
   01 INPUT-STRING PICTURE 9(11).
   01 UPC-DIGITS.
      02 UPC-DIGIT PICTURE 9 OCCURS 11 TIMES.
   01 ITERATOR     PICTURE 9(2).
   01 CHECKSUM     PICTURE 9(3).
PROCEDURE DIVISION.
MAIN-PROCEDURE.
    DISPLAY 1 UPON ARGUMENT-NUMBER.
    ACCEPT INPUT-STRING FROM ARGUMENT-VALUE.
    MOVE INPUT-STRING TO UPC-DIGITS.
    PERFORM VARYING ITERATOR FROM 1 BY 2 UNTIL ITERATOR IS GREATER THAN 11
      ADD UPC-DIGIT(ITERATOR) TO CHECKSUM GIVING CHECKSUM
    END-PERFORM.
    MULTIPLY CHECKSUM BY 3 GIVING CHECKSUM.
    PERFORM VARYING ITERATOR FROM 2 BY 2 UNTIL ITERATOR IS GREATER THAN 10
      ADD UPC-DIGIT(ITERATOR) TO CHECKSUM GIVING CHECKSUM
    END-PERFORM.
    MOVE MOD(CHECKSUM,10) TO CHECKSUM.
    IF CHECKSUM IS EQUAL TO 0 THEN
       DISPLAY CHECKSUM
    ELSE
       SUBTRACT CHECKSUM FROM 10 GIVING CHECKSUM
       DISPLAY CHECKSUM
    END-IF.
    STOP RUN.
END PROGRAM UPC-CHECK.