The World's Hardest Riddle
According to legend, Einstein devised this puzzle as a child and claimed that 98% of people cannot solve it. There are no tricks, no wordplay, and only one correct answer. All you need is logic... and patience.
Five houses stand in a row, each painted a different color. Each house is occupied by a person of a different nationality. Each person drinks a different beverage, smokes a different brand of cigars, and keeps a different pet.
Who keeps the fish?
Your 15 clues
The Answer
The German keeps the fish.
| # | Color | Nationality | Beverage | Cigar | Pet |
|---|---|---|---|---|---|
| 1 | Yellow | Norwegian | Water | Dunhill | Cats |
| 2 | Blue | Dane | Tea | Blends | Horses |
| 3 | Red | Brit | Milk | Pall Mall | Birds |
| 4 | Green | German | Coffee | Prince | Fish ✓ |
| 5 | White | Swede | Beer | BlueMaster | Dogs |
Step-by-step solution
Clue 9 tells us the Norwegian is in house 1 — a fixed starting point. Clue 14 says the Norwegian lives next to the blue house. Since he's in house 1, his only neighbor is house 2.
Clue 4 says green is immediately left of white. The only positions where that works are 4–5 (since house 2 is already blue). Clue 5 then tells us the green house owner drinks coffee.
Clue 1 says the Brit lives in the red house. Houses 2, 4, and 5 are taken (blue, green, white). House 1 belongs to the Norwegian. That leaves house 3 as the only candidate for red.
Colors assigned so far: house 2 = blue, 3 = red, 4 = green, 5 = white. The only color left for house 1 is yellow. Clue 7 says the yellow house owner smokes Dunhill.
Clue 8 is simple: the center house (house 3) drinks milk. We already know house 3 is the Brit.
Clue 11 says the horse owner is next to the Dunhill smoker (house 1). So horses must be in house 2. Clue 10 says the Blends smoker is next to the cat owner — testing Blends in house 2 is consistent with cats in house 1 or 3, which we'll confirm shortly.
Clue 15 says the Blends smoker (house 2) has a neighbor who drinks water. Neighbors are houses 1 and 3. House 3 drinks milk, so house 1 drinks water. Clue 3 says the Dane drinks tea — the only unassigned nationality for house 2 fits: Dane in house 2 drinking tea.
Clue 10 says the Blends smoker (house 2) lives next to the cat owner. Neighbors are house 1 and house 3. House 3 is the Brit — whose pet will turn out to be birds (via Pall Mall). So cats can only go to house 1.
Clue 12 says the BlueMaster smoker drinks beer. Beverages still unassigned: beer and coffee (house 4 already has coffee). Beer must go to house 5 — making house 5 the BlueMaster smoker. Clue 6 says the Pall Mall smoker keeps birds. The only house without a pet and cigar yet is house 3, so the Brit smokes Pall Mall and keeps birds.
Nationalities placed: Norwegian (1), Dane (2), Brit (3). Remaining: German and Swede in houses 4 and 5. Clue 2 says the Swede keeps dogs — house 5 must be the Swede with dogs. That puts the German in house 4. Clue 13 says the German smokes Prince. The only pet left is fish — and it belongs to the German in house 4.