And everybody moves two rooms up. Mentor and the student discuss who moves where. Usually the student happily explains the solution. Mentor asks him to write down what infinity plus thousand is. All these problems were easy to solve.
Mentor discusses the student's suggestions.
He thought very hard, then picked up his radio and asked everybody to move to a room with number twice as large as his current room's number. So the person from room 1 moved to room 2, and so on. Mentor draws the movements, asking the student where should people from different rooms go. Now let's look at the rooms. The guy from room 1 went to room 2, so the first one is empty.