80 hard Sudoku puzzles

The benefits of Sudoku are endless. It Improves your memory and logical thinking. It improves your critical thinking and ability to solve problems. It simulates your mind. Increases your concentration. But most importantly it's fun and addictive !Our books are made with extremely durable covers. The paper quality is durable and high grade.(Not coloring book paper). You can write and erase without fear of tearing the paper. Only one puzzle per page makes it easy to read.