Solve this please.

Bobo visits the local high school on a Saturday morning and finds that all of the school's 1,000 lockers are neatly closed. So, he starts at one end of the school and opens them all. Then he goes back to the start and closes EVERY OTHER locker (lockers 2, 4, 6, and so on). Then he goes back to the start and visits EVERY THIRD locker: if it is open, he closes it; if it is closed, he opens it. He again returns to the start and this time visits EVERY FOURTH locker. If it is open, he closes it; if it is closed, he opens it. He continues to return to start, and then visits EVERY FIFTH, then EVERY SIXTH, and so on until he has done this process 1,000 times. Then he gets bored and goes home. WHAT BOBO NEEDS TO KNOW IS: At the end, how many of the school's 1,000 lockers are left open, and which ones are they? Maybe if you give Bobo some line-by-line steps or you draw a few pictures of what Bobo has to do, Bobo will figure everything out