There are 1000 light bulbs and 1000 tutors. All light bulbs are off. Tutor 1 goes flipping light bulb 1,2,3,4... tutor 2 then flips 2,4,6,8... tutor 3 then 3,6,9...etc until all 1000 tutors have done this. What is the status of light bulb 25? 93? 576? Is there a general solution to find out the status of any light bulb? How many light bulbs are on after all 1000 tutors have gone by?
Not homework but a UK university interview question. Please help.