Basic COBOL Calculator – Code Review Stack Exchange

Small Calculator I made for myself while trying to learn COBOL for fun. Compiler used is GNUCOBOL. Just asks for input and will either do multiplication, subtraction, or addition. Completes run after input is asked.

MATH
       IDENTIFICATION DIVISION.
       PROGRAM-ID. MATH.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 INP PIC A(14).
       01 NUM1 PIC 9(7).
       01 NUM2 PIC A(2).
           88 PLU VALUE "+".
           88 AIDS VALUE "-".
           88 MULT VALUE "*".
       01 NUM3 PIC 9(15).
       01 ANS PIC 9(8).
       PROCEDURE DIVISION.
           DISPLAY "Input: "
           ACCEPT INP.
           UNSTRING INP DELIMITED BY SPACE
               INTO NUM1, NUM2, NUM3
           END-UNSTRING.
           IF NUM2 = "+" THEN
               ADD NUM1 NUM3 GIVING ANS
           ELSE 
               IF NUM2 = "-" THEN
                   SUBTRACT NUM1 FROM NUM3 GIVING ANS
               ELSE 
                   IF NUM2 = "*" THEN
                       MULTIPLY NUM1 BY NUM3 GIVING ANS
           END-IF.
           DISPLAY ANS.
           STOP RUN.

COBOL documentation isn’t as great compares to languages like C++ or Javascript, so I struggled a bit.