IDENTIFICATION DIVISION.
       PROGRAM-ID. DIGITAL-ROOT.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 VARIABLES.
          03 INPUT-NUMBER     PIC 9(16).
          03 INPUT-DIGITS     REDEFINES INPUT-NUMBER,
                              PIC 9 OCCURS 16 TIMES.
          03 DIGIT-SUM        PIC 999.
          03 DIGIT-NO         PIC 99.
          03 PERSISTENCE      PIC 9.

       01 OUTPUT-FORMAT.
          03 O-NUMBER         PIC Z(15)9.
          03 FILLER           PIC X(16) VALUE ': PERSISTENCE = '.
          03 O-PERSISTENCE    PIC Z9.
          03 FILLER           PIC X(9) VALUE ', ROOT = '.
          03 O-ROOT           PIC Z9.

       PROCEDURE DIVISION.
       BEGIN.
           MOVE 627615 TO INPUT-NUMBER, PERFORM FIND-DIGITAL-ROOT.
           MOVE 39390 TO INPUT-NUMBER, PERFORM FIND-DIGITAL-ROOT.
           MOVE 588225 TO INPUT-NUMBER, PERFORM FIND-DIGITAL-ROOT.
           MOVE 393900588225 TO INPUT-NUMBER, PERFORM FIND-DIGITAL-ROOT.
           STOP RUN.

       FIND-DIGITAL-ROOT.
           MOVE ZERO TO PERSISTENCE.
           MOVE INPUT-NUMBER TO O-NUMBER.
           PERFORM SUMMATION UNTIL INPUT-NUMBER IS LESS THAN 10.
           MOVE INPUT-NUMBER TO O-ROOT.
           MOVE PERSISTENCE TO O-PERSISTENCE.
           DISPLAY OUTPUT-FORMAT.

       SUMMATION.
           MOVE ZERO TO DIGIT-SUM.
           ADD 1 TO PERSISTENCE.
           PERFORM ADD-DIGIT VARYING DIGIT-NO FROM 1 BY 1
               UNTIL DIGIT-NO IS GREATER THAN 16.
           MOVE DIGIT-SUM TO INPUT-NUMBER.

       ADD-DIGIT.
           ADD INPUT-DIGITS(DIGIT-NO) TO DIGIT-SUM.