# Do You Do Shikaku?

Keeping a sharp cognitive fitness level means continually engaging in mental exercises, using multiple senses, having a growth mindset, doing so often, and repeatedly. I like to find new challenges and this summer is no exception. A while back I remember being introduced to a puzzle named Shikaku. It was created by Nikoli, the Japanese creators of the ever-popular Sudoku puzzle.

The Shikaku puzzle is a square or rectangular frame divided into small squares by dashed lines. Some of these squares contain numbers. The goal is to divide the grid into rectangles so that each number is in its own rectangle. The size of the rectangle must correspond to the number within the rectangle. So, a “3” must be in a rectangle consisting of three boxes, a “6” in a rectangle consisting of 6 boxes, and so on. There is only one possible way to complete each puzzle correctly. The grid must be divided into rectangles (and not into irregular shapes) which is the clue that relates to a specific number. For example, the number “4” can be either in a square that is 2 x 2 or a rectangle that is 1 x 4. However, 5 (or any other prime number) can only be in a rectangle that is 1 x 5. Recognizing this give players insight as they determine where to place the rectangles.

There are two pages of puzzles already prepared for you. If you want even more puzzles than are provided here, larger grids can be found online and Enjoy, share with friends and students, and stay fit!!