50g

Hello rick, you completely forgot that you have to enter the operations
in Reverse Polish Notation (Don't worry I steel find myself doing that
mistake) and also you are missing one THEN and there is an extra END,
and the world "DEFAULT" should be right before the last end, so it
should be like this:

Line Number   Program

1                             << ¨ A

2                             <<

3                            CASE

4                              A 5 <

5                              THEN A 2 * END

6                               A 10 <

7                              THEN gTWOh END

8                               A 15 <

9                                THEN A 2/ END

10                              "DEFAULT"

11                               END

12                                >>

13                                >>