I really like it, very well made all around (if I just could read romanian). Surprised you only got second. A small tip: You can call Greenfoot.start() to virtually press the "Run" button so the user doesn't have to do it

10: Remove ln from println so that the output would really be in one line. 23: To make it more readably, you could write Integer num1 = 100, num2 = 100, num3 = 500, num4 = 500;

Q9 is correct (unless you assume that the output is additional to the ones in the switch). But the explaination for [23] should be improved, that's true. The range -128 to 127 is cached by the jvm.

However feel free to try and fix it, I would very much appreciate it! I had exactly this problem now several times, and I can't figure out how to get rid of it.