Rectangles (Shikaku) Strategy: 5 Techniques

1. Primes are strips

2, 3, 5, 7 and 11 can only be 1 wide. Look along the row and column for room.

2. Count the shapes

A 6 can be 1×6, 2×3, 3×2 or 6×1, and each shape can slide to several positions. Rule out any that would swallow another number or run off the grid. Often one stays.

3. Cells only one number can reach

Pick an empty cell and ask which numbers could cover it. If only one can, the cell is in that number's rectangle, and that often fixes the shape.

4. Walls and corners

Numbers near an edge have fewer options. Start there.

5. Big numbers first

A 12 or 16 takes a lot of room and leaves little choice. Placing it splits the grid into smaller parts that are easier to finish.

Last updated 2026-10-20