Help me in solving PLSQL04 problem

help
,
1

My issue

which hidden case mising in code

My code

-- Declare variables
DECLARE
  num1 NUMBER := 10;
  num2 NUMBER := 5;
  result NUMBER;
BEGIN
  -- Perform addition
  result := num1 + num2;
  DBMS_OUTPUT.PUT_LINE('' || result);

  -- Perform subtraction
  result := num1 - num2;
  DBMS_OUTPUT.PUT_LINE('' || result);

  -- Perform multiplication
  result := num1 * num2;
  DBMS_OUTPUT.PUT_LINE('' || result);

  -- Perform division
  result := num1 / num2;
  DBMS_OUTPUT.PUT_LINE('' || result);
END;
/

Learning course: Database management systems
Problem Link: Sample syntax in Database management systems