The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.
What can a student say to prevent his being expelled from school?
I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?