Shikaku (Rectangles)

Tap two opposite corners to place a rectangle. Cover the whole grid without overlapping. Every rectangle must contain exactly one number, equal to its number of squares.

A 6 can be a 2 × 3 or 1 × 6 rectangle, if it fits the grid and contains no other number. Squares count as rectangles too.

To resize a rectangle, select two new corners around the same number. Other rectangles stay in place. Tap within a rectangle, then Erase to remove it. Cancel clears the first corner. Undo and redo last for this session.

Keyboard: Tab to the board. Use arrows to move, Enter or Space to select each corner, Escape to cancel, and Delete to erase the current rectangle. H asks for a hint; Ctrl/Cmd+Z undoes, Ctrl/Cmd+Shift+Z or Ctrl/Cmd+Y redoes.

5 × 5 and 7 × 7 select board sizes. Progress saves in this browser when storage is available; it does not sync across devices. Reload restores the board, but not undo history. Puzzles come from a finite original bank.

Look at a number's possible rectangle shapes and check which fit without taking another number's squares. Every uncovered square must eventually belong to one numbered rectangle.

Hint reasons from your current rectangles; Apply hint places its suggested rectangle. A contradiction means an earlier rectangle needs changing. Undo or erase it to try another shape.

Reveal solution shows the full answer and marks the puzzle as assisted. It is separate from a hint.