Q.> A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:
There are 1000 lockers and 1000 students in the school. The principal asks the 1st student to go to every locker and open it. Then he has the 2nd student go to every 2nd locker and close it. The 3rd goes to every 3rd locker and, if it is closed, he opens it, and if it is open, he closes it. The 4th student does this to every 4th locker, and so on. After the process is completed with the 1000th student, how many lockers are open ?