Question

There are 200 lockers in your school, numbered 1 through 200 consecutively. The lockers are all closed to begin. Student #1 walks down the corridor and opens all the lockers that are numbered with a multiple of 1, thereby all the lockers are opened. Student #2 then walks down the corridor and changes the status (closed lockers are opened; open lockers are closed) of all the lockers that are numbered with a multiple of 2 (note that in the case of Student #2, this only involved closing lockers). Student #3 then walks down the corridor and changed the status of all the lockers that are numbered w

Answer 1

This is an old chestnut, but I've always liked it.

Shame you butchered it, though.