In order to restrict participation, I created passwords which need to be inserted to be able to proceed. I then check via logic whether the numerical password is correct.
Since, there is not a good option for that, I created a question which requires a number as answer. However, when I copy&paste a password in there (similar to 8484859). It first gives an error “max characters used” and after 2-4 seconds, I can successfully submit the answer.