The answer to the green-eyed dragon puzzle

Remember the post we made about the most difficult logic puzzle in the world about the green-eyed dragons? (if not, you should definitely read this first).


Brace yourself, because here comes to answer!


On the 100th midnight, every dragon will turn into a sparrow!


Why? Well, to understand the situation, we first need to simplify it. So, let’s assume there is only 1 dragon on the island. When you say that at least 1 dragon has green eyes, he instantly knows it must be him and he’ll become a sparrow that same night. 


When there are 2 dragons on the island and you say that at least 1 of them has green eyes, they’ll look into each other’s eyes and see that the other has green eyes. However, they don’t know yet if they themselves have green eyes as well. So they sit and wait until midnight and notice that both don’t turn into a sparrow. That can only mean that both dragons saw the same in each other’s eyes: green, since if they hadn’t seen that, they’d have known they’d be the only one with green eyes.


So, now that we got that, let’s go to a situation with 3 dragons. When you tell them that at least 1 has green eyes and if 1 dragon assumes that it doesn’t have green eyes, then the same thing would happen to the other 2 dragons as in the above situation with only 2 dragons. They would sit out the first night and notice that the other doesn’t become a sparrow. After all, if only 1 dragon would have green eyes, he would turn into a sparrow on the 1st midnight since he would see his 2 companions having no green eyes. So, after the 1st night, all dragons know that there must be at least 2 dragons on the island with green eyes, but they don’t know yet if they themselves have green eyes. If 1 dragon assumes that he doesn’t have green eyes, then the other two would of course see that and realize they are the ones. So they would become sparrows on the second night. But they don’t….. so all dragons know that they have green eyes after that and on the 3rd midnight, they all turn into a sparrow.


You can continue this reasoning up to 100 dragons who would then find out on the 100th night that they themselves must have green eyes.


Too complicated? No worries! After all, dragons don’t even exist! Or….. do they

Share this post with your friends

Check our Mystery Games

Escape Road Trips
Escape Road Trips
Probably the largest escape room in the world! A 3-day adventure full of puzzles and fun.


Stay tuned

Like this? Leave your name and email and we will keep you posted with latest updates and new editions on our escape road trips, mystery escape games and city games.
Get a 20% discount on all our Escape Games if you sign up now.

By signing up to the newsletter, you agree with our privacy policy.