Solving shikaku puzzles is a great way to increase your mental productivity. These puzzles require logical thinking, problem-solving skills, and spatial reasoning. By regularly engaging in shikaku puzzles, you can improve your concentration, memory, and overall cognitive abilities. The challenge of fitting the numbers into the grid while following the rules of the game can help to enhance your critical thinking and decision-making skills. Furthermore, solving shikaku puzzles can also provide a sense of accomplishment and satisfaction, which can boost your confidence and motivation. So, if you're looking for a fun and effective way to exercise your brain and improve your mental productivity, give shikaku puzzles a try!