Shikaku
Einstein
00:00
Classic
Einstein Shikaku — what to expect
Einstein is expert’s 10×10 board plus the deepest step in the puzzle. A placement can be wrong because of what it leaves behind rather than anything about the rectangle itself: draw it, and some cell nearby is left with no clue that could ever reach it. That stranded cell is the proof the placement was wrong. Every board still has exactly one solution and is reachable by logic — the step is deeper, not a guess.
How to play Shikaku
- Divide the whole grid into rectangles. Every square ends up inside exactly one of them.
- Each rectangle contains exactly one number.
- That number is the rectangle’s AREA — how many squares it covers. A 6 can be 1×6, 6×1, 2×3 or 3×2, and nothing else.
- So a 1 is its own square, and a prime number can only be a single strip.
- Start where there is no choice: a number whose rectangle fits only one way, usually against an edge or a corner.
- Two numbers can never share a rectangle, which rules out a great many shapes before you try them.
- Every puzzle has one solution, reachable by logic alone, and every board has a move you can make from the empty grid.