There are 100 rooms in a building, which has one light bulb in each room. The lights are intially all switched off. Now, there are 100 people. The first person enters every room, and switches on the lights. The second one goes to every second room and does the opposite of what already exists, i.e. if the light is switched on , he switches it off and vice versa.
The person goes to every 3 rd room and does the same, the fourth person to every 4th room and does the same. Likewise all the 100 people follow this. After all the 100 people have done this process, how many rooms will remain switched on at the end?
The person goes to every 3 rd room and does the same, the fourth person to every 4th room and does the same. Likewise all the 100 people follow this. After all the 100 people have done this process, how many rooms will remain switched on at the end?
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