You've been sent to prison, but the prisons where you are from are very clever. They do not just lock you up, they put you in a room with 2 doors.

Door A is guarded by an evil dragon that will kill anyone who leaves.

Door B is simply a hallway, with an odd ceiling, it's the strongest magnifying glass on earth! What's so bad about this? It magnifies the sun so strong it'll burn you to a crisp the second you leave.

They also went through extra measures to make sure you don't live through 24 hours, the back wall is slowly enclosing on you. There is no open ceiling in the prison room, so don't try wall jumping Mario style once the wall encloses a bit.

How can you escape?

  • $\begingroup$ No, there's no vents. $\endgroup$
    – warspyking
    Commented Oct 25, 2014 at 12:12
  • 6
    $\begingroup$ I could take that dragon... $\endgroup$ Commented Oct 27, 2014 at 12:43
  • 1
    $\begingroup$ @Golden 'course you could Golden Dragon! $\endgroup$
    – warspyking
    Commented Oct 27, 2014 at 17:51
  • 1
    $\begingroup$ Relevant: magnifying skyscraper melts car. $\endgroup$ Commented Aug 27, 2015 at 14:13
  • $\begingroup$ @rand al'thor lol! $\endgroup$
    – warspyking
    Commented Aug 27, 2015 at 15:12

4 Answers 4


In the 24 hours you have you there must be night time.

Open the door B one slight bit to find if there is light in the next room, as soon as its dark, you know its night and the magnifying glass wont harm you and you can leave.

If opening the door would kill you either ways, just feel the heat of the door B, that should give an indication if the other room is hot or cold.

  • 1
    $\begingroup$ Bingo! I can accept this in 7 min. $\endgroup$
    – warspyking
    Commented Oct 25, 2014 at 12:19
  • 13
    $\begingroup$ What if we're in summer in the arctic? $\endgroup$
    – aaazalea
    Commented Oct 27, 2014 at 18:29
  • 8
    $\begingroup$ @JakobWeisblat after a quick google search I've concluded that the arctic does not have dragons so you should just go out the dragon door $\endgroup$ Commented Aug 28, 2015 at 15:21

The magnifying glass will only magnify the sunlight in a single spot (or a certain area, but certainly not the whole hallway). So go through door B, and walk through the hallway avoiding the hotspots.

  • 1
    $\begingroup$ while it is true the most hot spot is very small (the more concentrated the better), it can be fixed to be bigger to cover the whole door (e.g aiming further) while still being lethal I think $\endgroup$
    – ajax333221
    Commented Oct 30, 2014 at 18:25
  • $\begingroup$ I agree with this answer. Why wait till nighttime if you won't get fried along the edges of the room? Anyone who keeps a dragon penned up should be relying on magic instead of technology anyway - so they probably really don't have any mechanism for making a magnifying glass big enough to fry an entire room. If they did, the floor would already be burned up and you could escape through secret tunnels. $\endgroup$
    – bgmCoder
    Commented Apr 8, 2015 at 1:18
  • $\begingroup$ What if the hallway is hourglass-shaped and you have to walk through the hotspot? $\endgroup$ Commented Aug 27, 2015 at 14:12
  • 1
    $\begingroup$ Sit in a corner, cry like a little baby, I suppose $\endgroup$
    – Mathias711
    Commented Aug 27, 2015 at 14:26

The question specifies that the dragon will kill you only if you leave. So, if we open both doors and wait for 24 hours, the dragon may eventually random walk into the magnified hallway, and you can go through dragon's door. Off course, am assuming, the dragon won't kill you if you don't leave, and that the size of doors is big enough for dragon, and that the dragon moves.


Open the door with the magnifying glass a jar, then open the door with the dragon (assuming it is opposite the door with the light and you have room to not be cooked alive), then completely open the magnifying door to expose the dragon who is probably interested in eating you to the light shining though the opposite door. Once the dragon is dead close the magnifying door and walk out the dragons door.

At least the dragon will be blinded by the intense light and you could use that to your advantage.


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