Partition the whole grid into rectangles, each containing exactly one numbered clue equal to its area.
A clue of 6 can be 1×6, 2×3 or 3×2, list the possible rectangles, then let neighboring clues eliminate options.
Prime-numbered clues (5, 7, 11…) have only one possible shape and are the best places to start.
Yes, it plays directly in your browser with no download or registration.
Each number is the exact area of the rectangle that contains it, and every rectangle holds exactly one clue.
No, any rectangle works as long as its area matches its clue and it contains no other clue.
Yes, each size and difficulty gets a fresh official board every day, all archived.
Shikaku (literally 'divide by squares') comes from the great Japanese puzzle tradition, and this version keeps everything that made it a classic while making it effortless to play daily. Each puzzle is a rectangular grid with number clues; you draw rectangles that must contain exactly one clue each, and that clue must equal the rectangle's cell count. The deductions start arithmetic, a prime clue like 7 can only be 1×7, and end geometric, as the remaining free space forces the shape of the last rectangles. Because every rectangle you place shrinks the free area, mid-game boards turn into a friendly negotiation between the factors you know and the spaces that remain. Four daily sizes serve everyone from beginners to experts, the drag-to-draw interface feels natural with mouse or finger, and validation is instant so wrong rectangles never sneak through. The daily archive keeps every past board playable, and hints reveal a single rectangle at a time, enough to unstick, never enough to spoil.