Shikaku puzzle
Shikaku is a Japanese logic puzzle, also called Rectangles or Divide by Box. It was invented in 1989 and published by the puzzle magazine Nikoli (history on Wikipedia).
Try today's daily boardHow to play
Divide the whole grid into rectangles. Each rectangle must contain exactly one number, and that number is the rectangle's area: a 6 needs a box of six cells, such as 2×3 or 1×6. Squares count as rectangles. When every cell belongs to a box and every box is correct, the puzzle is solved.
To draw a box, drag from one corner to the opposite corner. On a phone you can also tap one corner and then the other. Tap a box to remove it, or draw over it to replace it. Boxes with a stripe are wrong: they hold no number, more than one number, or the wrong number of cells.
How to solve Shikaku
- Write out the shapes a number can take. A 6 can be 1×6, 6×1, 2×3 or 3×2. A 4 can be 1×4, 4×1 or 2×2. Then remove every shape that runs off the board or covers another number.
- Start with numbers that fit one way. Big numbers in corners and along edges often have only one shape left. Place those boxes first; each one takes cells away from its neighbours.
- Prime numbers make straight lines. A 5 or a 7 can only be 1 cell wide, so it runs straight across or straight down. If another number blocks one direction, the other is forced.
- Look for cells only one number can reach. If an empty cell can only be covered by one number's possible boxes, that box must include the cell. This is the key step on medium and hard boards.
- Check what is left. After each box, some numbers lose options. Go round the board again until every number has exactly one shape.
Questions
Does every Shikaku puzzle have one solution?
Yes. Before a board is shown, our solver confirms it has exactly one solution and that it can be finished by deduction alone, without guessing.
What size are the boards?
Practice offers easy 5×5, medium 7×7 and hard 9×9 boards. The daily Shikaku is a medium 7×7 board, the same for every player.
What is the difference between easy, medium and hard?
Easy boards can be solved by placing numbers that fit only one way. Medium and hard boards always need at least one step where an empty cell can only be reached by one number.
How is the daily score calculated?
The daily score starts at 3,000 and drops by 10 points per second from your first move, with a minimum of 100. The server checks your finished grid before it records the score.
Made by Young at PuzzleGame.win · Published