Rectangles

The grid is dotted with numbers. Divide the whole board into rectangular blocks so that each rectangle contains exactly one number, and that number is the area of the rectangle (its width times its height). Every cell must belong to exactly one rectangle.

• Each rectangle holds one and only one number.
• A number must equal the count of cells in its rectangle.
• No cell is left out and no rectangles overlap.

• Desktop: click and drag to draw a rectangle around a number.
• Phone & tablet: drag across cells to outline a rectangle.

• Daily seeded puzzle shared by all players.
• Practice with fresh boards.

• Start with 1s (single cells) and large primes, their shapes are the most constrained.
• Use board edges as anchors; a number near a corner often has only one possible rectangle.

Shikaku has a named inventor and a precise year — Yoshinao Anpuku, a mathematics student at Kyoto University, devised it in 1989, and Nikoli published it under that name before it spread to other magazines and into video games.

The rule is a single sentence: divide the whole grid into rectangles, each containing exactly one number, and each with an area equal to that number. Nothing may overlap and nothing may be left over.

Its difficulty comes from factorisation. A 12 can be 1×12, 2×6, 3×4 or their transposes, so every number is a set of possible shapes rather than one, and the solve is the work of finding which combination tiles the grid exactly — a packing problem wearing the clothes of an arithmetic one.

Rectangles is an original build of the area-division logic puzzle, free to play in your browser with a fair daily and endless practice. Made in-house at PlayPendium.

A free, original browser game on PlayPendium. No download, no install.