Question

100 Doors Riddle

Answer 1

There are 100 closed doors (number them 1 to 100). Open every door. Then close every 2nd door (every even-numbered door.) Then change the status of every third door (close it if it is open and open it if it is closed). Keep going with this pattern until you are changing the status of every 100th door (so just the last door).

Which doors are open in the end?