The following riddle is claimed to have been written by Einstein as a boy. It's also sometimes attributed to Lewis Carrol, although there's no evidence that either of them actually wrote it. Either way, it's fiendishly clever and is popularly called "Einstein's Riddle". It's rumored that only 2% of the world can solve it.

See if you can figure it out:

There are five houses in five different colors in a row. In each house lives a person with a different nationality. The five owners drink a certain type of beverage, smoke a certain brand of cigar and keep a certain pet. No owners have the same pet, smoke the same brand of cigar, or drink the same beverage. Other facts:

1. The Brit lives in the red house.

2. The Swede keeps dogs as pets.

3. The Dane drinks tea.

4. The green house is on the immediate left of the white house.

5. The green house's owner drinks coffee.

6. The owner who smokes Pall Mall rears birds.

7. The owner of the yellow house smokes Dunhill.

8. The owner living in the center house drinks milk.

9. The Norwegian lives in the first house.

10. The owner who smokes Blends lives next to the one who keeps cats.

11. The owner who keeps the horse lives next to the one who smokes Dunhill.

12. The owner who smokes Bluemasters drinks beer.

13. The German smokes Prince.

14. The Norwegian lives next to the blue house.

15. The owner who smokes Blends lives next to the one who drinks water.

The question is: who owns the fish?

There are no tricks, all it requires is simple logic. Those that haven’t the patience to work it out can watch PoETheeds' video, which takes you through the process of solving it step by step.