Problem Statement

Show a loop which prints random numbers (each number newly generated each loop) from 0 to 19 (inclusive). If a number is 10, stop the loop after printing it, and do not generate any further numbers.
Otherwise, generate and print a second random number before restarting the loop.
If the number 10 is never generated as the first number in a loop, loop forever.

Let's start with the solution:

MODULE LoopBreak;
IMPORT
  RandomNumbers,
  Out;

PROCEDURE Do();
VAR
  rn: LONGINT;
BEGIN
  LOOP
    rn := RandomNumbers.RND(20);
    Out.LongInt(rn,0);Out.Ln;
    IF rn = 10 THEN EXIT END;
    rn := RandomNumbers.RND(20);
    Out.LongInt(rn,0);Out.Ln
  END
END Do;

BEGIN
  Do
END LoopBreak.