Guide
Einstein's Riddle Explained
The most famous logic puzzle in the world,
and the honest story behind it.
Five houses, five neighbours, two questions.
Five houses stand in a row, each painted a different colour.
In each house lives a person of a different nationality.
Each of the five drinks a different drink, smokes a different brand, and keeps a different pet.
You get fifteen clues, and two questions.
Who drinks water?
Who owns the zebra?
The clues come in two kinds.
A few are absolute, like "the Norwegian lives in the first house" and "milk is drunk in the middle house".
Most are relative, like "the green house is immediately to the right of the ivory house" or "the Norwegian lives next to the blue house".
Nothing else is given.
And yet the answer is fully determined.
Einstein didn't write it, and 2% is made up.
The puzzle first appeared in Life International magazine on 17 December 1962, under the title "Who Owns the Zebra?".
The solution, and a list of readers who cracked it, ran the following March.
Somewhere along the way the internet decided that Albert Einstein wrote it as a boy.
Other versions credit Lewis Carroll.
There is no evidence for either.
Einstein died in 1955, seven years before the puzzle was printed, and nothing in the original mentions him.
The same goes for the line that "only 2% of the world's population can solve it".
Nobody has ever found where that number came from.
It's a hook, not a statistic.
Anyone who can follow a clue can solve this puzzle, and the next section shows you how.
The version most people meet today is a later rewrite.
The nationalities change, the cigarettes become cigars, and the zebra becomes a fish.
Same structure, same logic, same trick.
Think in positions, not in pairs.
Forget the usual categories-against-categories grid for a moment.
This puzzle is about positions, so draw five columns for the five houses and five rows for the five categories.
Twenty-five cells, and you will fill every one of them.
| House 1 | House 2 | House 3 | House 4 | House 5 | |
|---|---|---|---|---|---|
| Colour | ? | Blue | ? | ? | ? |
| Nationality | Norwegian | ? | ? | ? | ? |
| Drink | ? | ? | Milk | ? | ? |
| Pet | ? | ? | ? | ? | ? |
| Brand | ? | ? | ? | ? | ? |
- Start with the absolute clues.
The Norwegian goes in house 1. Milk goes in house 3. Two cells filled before you've had to think. - Chain the neighbours.
"The Norwegian lives next to the blue house" now has only one reading, because house 1 has just one neighbour. House 2 is blue. - Place the pairs.
The green house is immediately to the right of the ivory one, so they sit side by side. House 2 is blue, so the pair can only be houses 3 and 4, or houses 4 and 5. The other colour clues decide which. - Cross out with the rest.
Every clue that ties a nationality to a colour, a drink or a brand removes options from a column. Keep going round the list. - Finish by elimination.
When four houses have a drink, the fifth drink belongs to the last house. That is how the water and the zebra fall out at the very end, not from any clue that names them.
Done properly, you never guess.
The Norwegian turns out to drink the water, and the Japanese neighbour keeps the zebra.
In the fish version, it's the German.
Nothing in it is difficult.
There are just fifteen clues, and the first time through, most of them give you nothing.
The trick is going round the list again after every new fact.
On the third pass the whole thing collapses.
Two kinds of clue. Everything else is elimination.
Strip the story away and the riddle has exactly two kinds of clue.
Anchors, which pin something to a position.
Neighbours, which tie two things to adjacent positions.
That's it.
Everything else is elimination.
Eitanium is built on those two clue types, on a 5×5 grid, with a fresh puzzle every time.
Anchor clues pin a number to a row.
Direction clues say which numbers sit next to each other.
It's the zebra puzzle you can play on the bus, and it never runs out.
A new zebra puzzle every day.
Eitanium is free on Google Play.
Level 1 is gentle on purpose.
