There is a row of 1000 lockers.
There is a line of 1000 students.
Student number 1 starts at the first locker and opens all 1000. Student number 2 starts at the second locker and closes every other one. Student number 3 starts at the third locker and goes to every third one, closing the open ones and opening the closed ones. Student number 4 does the same with every fourth locker and so on down the line... After all 1000 students have gone how many lockers are open and which ones are they?
Please help! There is proboly a simple solution but we couldnt figure it out for the life of us. Please let us know how you solve it.