It’s Earth 2. Everything here is the same as on our planet Earth, but the only difference is that here, the occupants are numbers form our world. Bill is the only human from Earth 1 to travel to Earth 2. As you progress along the chapter, Bill observes the way the occupants (numbers) of Earth 2 behave and would eventually realize that the laws of numbers hold good everywhere in the universe!
So, Bill enters a room, whose nameplate read, Room N. He notices that, inside the room, the occupants were numbers which he used on a daily basis to count stuff around.
If Bill calls the smallest number among them, which number would turn up?
Natural numbers begin from 1. Because we use these numbers to count, these are also called counting numbers. We start counting from 1 and hence it is the smallest natural number. The relevance of the ‘N’ in Room N comes from the fact that Natural numbers are represented by N.