Einstein's Riddle
Who owns the fish?
Five houses in a row, each one a different color. In each lives someone from a different country, who drinks one drink, smokes one brand of tobacco and keeps one pet. Nobody repeats anything.
The clues
Tap a clue to cross it out
The grid fills in what follows from your marks
| Color | Country | Drink | Tobacco | Pet | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| red | green | white | yellow | blue | British | Swede | Dane | Norwegian | German | tea | coffee | milk | beer | water | Pall Mall | Dunhill | Blends | Bluemaster | Prince | dog | birds | cat | horse | fish | ||
| House | House 1 | |||||||||||||||||||||||||
| House 2 | ||||||||||||||||||||||||||
| House 3 | ||||||||||||||||||||||||||
| House 4 | ||||||||||||||||||||||||||
| House 5 | ||||||||||||||||||||||||||
| Pet | dog | |||||||||||||||||||||||||
| birds | ||||||||||||||||||||||||||
| cat | ||||||||||||||||||||||||||
| horse | ||||||||||||||||||||||||||
| fish | ||||||||||||||||||||||||||
| Tobacco | Pall Mall | |||||||||||||||||||||||||
| Dunhill | ||||||||||||||||||||||||||
| Blends | ||||||||||||||||||||||||||
| Bluemaster | ||||||||||||||||||||||||||
| Prince | ||||||||||||||||||||||||||
| Drink | tea | |||||||||||||||||||||||||
| coffee | ||||||||||||||||||||||||||
| milk | ||||||||||||||||||||||||||
| beer | ||||||||||||||||||||||||||
| water | ||||||||||||||||||||||||||
| Country | British | |||||||||||||||||||||||||
| Swede | ||||||||||||||||||||||||||
| Dane | ||||||||||||||||||||||||||
| Norwegian | ||||||||||||||||||||||||||
| German | ||||||||||||||||||||||||||
Tap a square to open it
House × Color
| red | green | white | yellow | blue | |
|---|---|---|---|---|---|
| House 1 | |||||
| House 2 | |||||
| House 3 | |||||
| House 4 | |||||
| House 5 |
Each square pairs two things. Tap a cell: ✕ if they don't go together, again for ◯ if they do, and once more to clear it.
The solution
See the solution
| House 1 | House 2 | House 3 | House 4 | House 5 | |
|---|---|---|---|---|---|
| Color | yellow | blue | red | green | white |
| Country | Norwegian | Dane | British | German | Swede |
| Drink | water | tea | milk | coffee | beer |
| Tobacco | Dunhill | Blends | Pall Mall | Prince | Bluemaster |
| Pet | cat | horse | birds | fish | dog |
- House 1 yellow · Norwegian · water · Dunhill · cat
- House 2 blue · Dane · tea · Blends · horse
- House 3 red · British · milk · Pall Mall · birds
- House 4 green · German · coffee · Prince · fish
- House 5 white · Swede · beer · Bluemaster · dog
The German owns the fish. He lives in the green house, the fourth one.
- The Norwegian lives in house 1 (clue 9), the blue house is house 2 (clue 14) and milk is drunk in house 3 (clue 8).
- The green house is immediately to the left of the white one (clue 4). They cannot be houses 1 and 2, or 2 and 3, because house 2 is blue. Nor 3 and 4: coffee is drunk in the green house (clue 5) and milk in house 3. So the green house is 4 and the white one is 5, and coffee is drunk in house 4.
- Red and yellow are left for houses 1 and 3. The red house is the Brit's (clue 1) and the Norwegian lives in house 1, so red is 3 and yellow is 1. Dunhill is smoked in the yellow house (clue 7), and the horse is next to it (clue 11): in house 2.
- The Norwegian is left with tea, beer and water. Tea is the Dane's (clue 3), and beer goes with Bluemaster (clue 12), but Dunhill is smoked in house 1. The Norwegian drinks water.
- The Blends smoker is the water drinker's neighbor (clue 15): the Blends smoker lives in house 2.
- Beer and tea are left for houses 2 and 5. House 2 smokes Blends, not Bluemaster, so beer and Bluemaster go in house 5, and tea in house 2: that is where the Dane lives.
- The German and the Swede are left for houses 4 and 5. The German smokes Prince (clue 13) and house 5 smokes Bluemaster: the German lives in house 4 and the Swede, with his dog (clue 2), in house 5.
- The only tobacco left, Pall Mall, belongs to house 3, and the birds go with it (clue 6).
- The cat is next to the Blends smoker (clue 10), in house 1 or 3. House 3 has the birds: the cat belongs to house 1.
- The only pet left is the fish, and the only house without a pet is house 4. The German owns the fish.
Enjoyed it? Try a case
Sudoku Detective is the same kind of reasoning with a map and a murder: each suspect says where they were, and there is only one solution.
Questions
Who owns the fish in Einstein's riddle?
The German. He lives in the green house, the fourth one, drinks coffee and smokes Prince.
Did Einstein write it?
There is no evidence that he did. The oldest known version appeared unsigned in Life International magazine in 1962, with a zebra instead of the fish. Nobody has ever measured the claim that only 2% of people can solve it either.
Does it have only one solution?
Yes. With the fifteen clues only one arrangement fits, and you can reach it without guessing: every step follows from a clue and from what is already placed.
Where do you start?
With the clues that give a position: the Norwegian lives in the first house and milk is drunk in the middle one. Once the Norwegian is placed, the blue house can only be the second.