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Lightbulb teaser

  1. Sep 16, 2009 #1
    there is a 1000 light bulbs in a room
    near each bulb there is a switch which turns the bulb near it on in a push of a button
    and turns it off in a second push of a button and turns it on again in the third push of a button.

    1000 students come into the room
    the first student pushing every button once (thus turning every lighbulb on)
    the second student pushes every second button (turned off every even place lightbulb)
    the third student pushes every third button

    how many lightbulbs will remain turned on
    if all 1000 students will act the same way as before(the 4th will push every 4th button etc..)
  2. jcsd
  3. Sep 16, 2009 #2
    Last edited by a moderator: Apr 24, 2017
  4. Nov 1, 2009 #3
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