100 Light bulbs | BRAINSTELLAR

general puzzles


Light bulbs are numbered 1 to 100, and kept off initially. The first person comes and toggles all the bulbs which are multiple of 1, i.e. they switch all bulbs to 'ON'. The second person toggles all multiples of 2, i.e. they turn the even bulbs 'OFF'. The third person comes and toggles all multiples of 3. This process continues till the 100th100^{\text{th}} person do their part. After this, how many bulbs are 'ON'?