src/com/company/Main.java

@@ -43,7 +43,7 @@ public class Main {
                         total = Calc.div(num1, num2);
                         System.out.println(total);
                     }
-                    default -> System.out.println("Unexpected value: " + op + " ...restarting program");
+                    default -> System.out.println("Unexpected value: '" + op + "' ...restarting program");
                 }
         }
     }