Wow. That was a complicated answer. But I understand it.
I did the formula you are supposed to do 4 seperate times with different numbers, but did not click the "magic ball". The answers always ended up with the same symbol. I see (I think I do at least) that there are only a few possible numbers you could come up with as an answer, and all of those have the same symbol. And only those answers change the symbol after each try.
Complicated, and "mathy", but cool