1. Check Digit - Mod 11 Please use speaker notes for additional information!

2. Find the check digit for 2530618: Mod 11 2 5 3 0 6 1 8 digits x8 x7 x6 x5 x4 x3 x2 multiply by weight 16 + 35 + 18 + 0 + 24 + 3 + 16 = 112 10 remainder 2 11)112 11 - 2 = 9 Number with check digit 25306189

3. Validate the check digit for 25306189: Mod 11 2 5 3 0 6 1 8 9 digits x8 x7 x6 x5 x4 x3 x2 x1 multiply by weight 16 + 35 + 18 + 0 + 24 + 3 + 16 + 9 = 121 11 11)121 Remainder is 0 When the remainder is 0, we know the number with the check digit is valid! Number with check digit 25306189

4. IDENTIFICATION DIVISION. PROGRAM-ID. MOD11CHK. AUTHOR. GROCER. ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. DATA DIVISION. WORKING-STORAGE SECTION. 01 ID-NUM. 05 DGT PIC 9 OCCURS 7 TIMES. 05 CHK-DGT PIC 9. 05 RDF-CHK-DGT REDEFINES CHK-DGT PIC X. 01 RDF-ID-NUM REDEFINES ID-NUM PIC X(8). 01 SUBSCRIPTZ. 05 SUB-DGT PIC 9 VALUE 1. 01 RESPONSEZ. 05 MENU-ANS PIC X VALUE SPACES. 05 RESPNSE PIC X VALUE SPACES. 05 MSG PIC X(29) VALUE SPACES. 01 WORK-ANS. 05 WT PIC 9 VALUE 8. 05 MULT-ANS PIC 99 VALUE 0. 05 SUM-DGTS PIC 999 VALUE 0. 05 DIVIDE-ANS PIC 99 VALUE 0. 05 REM-ANS PIC 99 VALUE 0. 05 SUBT-ANS PIC 99 VALUE 0. Mod 11 CHK-DGT must be redefined as a character field to accommodate the X that might be there. I have defined the number in WS as having 7 digits. I have then added the 8th digit which is the check digit and redefined it. I have then redefined the whole so I can move the entire number with the check digit even if the check digit is X. These are the work areas that I have set up to do the calculation. Note that WT which stands for weight starts with an initial value of 8. This will need to be reset if I am calculated multiple check digits.

5. SCREEN SECTION. 01 MENU-SCR. 05 VALUE "MENU" BLANK SCREEN LINE 5 COL 30. 05 VALUE "1 - CALCULATE CHECK DIGIT" LINE 8 COL 10. 05 VALUE "2 - VALIDATE CHECK DIGIT" LINE 9 COL 10. 05 VALUE "3 - END PROCESSING" LINE 11 COL 10. 05 VALUE "ENTER SELECTION" LINE 13 COL 20. 05 TAKE-IN-MENU-ANS LINE 13 COL 36 PIC X TO MENU-ANS. 01 TAKE-IN-ID-SCR. 05 VALUE "PLEASE ENTER NEW ID" BLANK SCREEN LINE 5 COL 10. 05 ID-INPUT LINE 5 COL 30 PIC 9(7) TO ID-NUM. 05 "PRESS ANY KEY TO CONTINUE..." LINE 10 COL 10. 05 TAKE-IN-FIRST-ANS LINE 10 COL 40 PIC X TO RESPNSE. 01 TAKE-IN-WHOLE-SCR. 05 VALUE "PLEASE ENTER ID TO VALIDATE" BLANK SCREEN LINE 5 COL 10. 05 WHOLE-INPUT LINE 5 COL 40 PIC X(8) TO RDF-ID-NUM. 05 "PRESS ANY KEY TO CONTINUE..." LINE 10 COL 10. 05 TAKE-IN-SECOND-ANS LINE 10 COL 40 PIC X TO RESPNSE. Mod11 Menu screen to choose to calculate the check digit or validate the check digit. If the user choose to calculate a check digit, then they will enter the 7 digit number here. If the user choose to validate a check digit, then they will enter the 8 digit number here.

6. 01 SHOW-RESULT-SCR. 05 VALUE "THE ID WITH CHECK DIGIT IS" BLANK SCREEN LINE 5 COL 10. 05 COMPLETED-ID LINE 5 COL 40 PIC X(8) FROM ID-NUM. 05 MSG-AREA LINE 7 COL 20 PIC X(30) FROM MSG. 05 VALUE "PRESS ANY KEY TO CONTINUE..." LINE 10 COL 10. 05 TAKE-IN-THIRD-ANS LINE 10 COL 40 PIC X TO RESPNSE. Mod 11 The results of calculating the check digit are displayed here along with the check digit.

7. PROCEDURE DIVISION. MAINLINE. PERFORM B-100-PROCESS. STOP RUN. B-100-PROCESS. DISPLAY MENU-SCR. ACCEPT MENU-SCR. PERFORM B-200-LOOP UNTIL MENU-ANS = "3". B-200-LOOP. IF MENU-ANS = "1" PERFORM B-300-CALC ELSE IF MENU-ANS = "2" PERFORM B-310-VALIDATE. DISPLAY MENU-SCR. ACCEPT MENU-SCR. Mod11 Initial take-in of the choice to calculate or verify from the menu. Checking of the menu to determine processing. Display and accept to take in menu choices after the initializing choice.

8. B-300-CALC. MOVE SPACES TO RDF-ID-NUM. MOVE SPACES TO MSG. DISPLAY TAKE-IN-ID-SCR. ACCEPT TAKE-IN-ID-SCR. MOVE 8 TO WT. MOVE 1 TO SUB-DGT. MOVE 0 TO SUM-DGTS. PERFORM B-400-MULT-ROUT 7 TIMES. DIVIDE SUM-DGTS BY 11 GIVING DIVIDE-ANS REMAINDER REM-ANS. SUBTRACT REM-ANS FROM 11 GIVING SUBT-ANS. IF SUBT-ANS = 10 MOVE "X" TO RDF-CHK-DGT ELSE IF SUBT-ANS = 11 MOVE 0 TO CHK-DGT ELSE MOVE SUBT-ANS TO CHK-DGT. DISPLAY SHOW-RESULT-SCR. ACCEPT SHOW-RESULT-SCR. Mod11 Take in screen to take in the identification number. Initialize weight at 8 since there will be 8 digits (currently there are 7), SUB-DGT (the pointer) to 1 and zero out the sum in SUM-DIGITS. Perform the routine to do the weight multiplication and accumulate the sum 7 times since there are 7 digits. Do the remaining math work of dividing to get the remainder and subtracting the remainder to get the answer. If the answer is 10 move X to the check digit, if 11 move 0 to the check digit, otherwise move the result of the subtraction to the check digit. Display the results of the calculation on the screen.

9. B-310-VALIDATE. MOVE SPACES TO RDF-ID-NUM. MOVE SPACES TO MSG. DISPLAY TAKE-IN-WHOLE-SCR. ACCEPT TAKE-IN-WHOLE-SCR. MOVE 8 TO WT. MOVE 1 TO SUB-DGT. MOVE 0 TO SUM-DGTS. PERFORM B-400-MULT-ROUT 7 TIMES. IF RDF-CHK-DGT = "X" ADD 10 TO SUM-DGTS ELSE ADD CHK-DGT TO SUM-DGTS. DIVIDE SUM-DGTS BY 11 GIVING DIVIDE-ANS REMAINDER REM-ANS. IF REM-ANS > 0 MOVE "****** ERROR IN ID ******" TO MSG ELSE MOVE "****** VALID ID ******" TO MSG. DISPLAY SHOW-RESULT-SCR. ACCEPT SHOW-RESULT-SCR. Mod 11 Take in screen to take in the whole identification number including the check digit.. Initialize weight at 8 since there are 8 digits, SUB-DGT (the pointer) to 1 and zero out the sum in SUM- DIGITS. Perform the routine to do the weight multiplication and accumulate the sum 7 times since there are 7 digits before the check digit. If the check digit is X, 10 is added to the sum otherwise the value of the check digit is added to the sum. Divide the sum of all 8 digits (including the check digit by 11 and get the remainder. If the remainder is 0 then the check digit is valid. If the remainder is greater than 0 an error message is moved to the screen. If the remainder is 0 a valid message is moved to the screen. The screen is displayed showing the number and a message confirming validity or highlighting an error.

10. B-400-MULT-ROUT. MULTIPLY DGT (SUB-DGT) BY WT GIVING MULT-ANS. ADD MULT-ANS TO SUM-DGTS. SUBTRACT 1 FROM WT. ADD 1 TO SUB-DGT. Mod 11 This is the routine that multiplies each digit by its weight and as each is multiplied, adds it to the total. It than subtracts 1 from the weight to prepare for the next pass through the routine and increments the subscript by 1 to again prepare for the next pass.