IDENTIFICATION DIVISION.
PROGRAM-ID. NTH-PROGRAM.
DATA DIVISION.
WORKING-STORAGE SECTION.
01  WS-NUMBER.
    05 N               PIC 9(8).
    05 LAST-TWO-DIGITS PIC 99.
    05 LAST-DIGIT      PIC 9.
    05 N-TO-OUTPUT     PIC Z(7)9.
    05 SUFFIX          PIC AA.
PROCEDURE DIVISION.
TEST-PARAGRAPH.
    PERFORM NTH-PARAGRAPH VARYING N FROM 0 BY 1 UNTIL N IS GREATER THAN 25.
    PERFORM NTH-PARAGRAPH VARYING N FROM 250 BY 1 UNTIL N IS GREATER THAN 265.
    PERFORM NTH-PARAGRAPH VARYING N FROM 1000 BY 1 UNTIL N IS GREATER THAN 1025.
    STOP RUN.
NTH-PARAGRAPH.
    MOVE 'TH' TO SUFFIX.
    MOVE N (7:2) TO LAST-TWO-DIGITS.
    IF LAST-TWO-DIGITS IS LESS THAN 4,
    OR LAST-TWO-DIGITS IS GREATER THAN 20,
    THEN PERFORM DECISION-PARAGRAPH.
    MOVE N TO N-TO-OUTPUT.
    DISPLAY N-TO-OUTPUT WITH NO ADVANCING.
    DISPLAY SUFFIX WITH NO ADVANCING.
    DISPLAY SPACE WITH NO ADVANCING.
DECISION-PARAGRAPH.
    MOVE N (8:1) TO LAST-DIGIT.
    IF LAST-DIGIT IS EQUAL TO 1 THEN MOVE 'ST' TO SUFFIX.
    IF LAST-DIGIT IS EQUAL TO 2 THEN MOVE 'ND' TO SUFFIX.
    IF LAST-DIGIT IS EQUAL TO 3 THEN MOVE 'RD' TO SUFFIX.