What's more satisfying than solving challenging sudokus?Sudoku puzzles offer a perfect mix of entertainment and brain gymnastics at the same time.The brain is like a muscle. It's getting stronger the more you train it. Solving sudoku puzzles is a perfect way to train your brain and make sure you stay sharp.This sudoku puzzle book is designed for you who want challenging - but not too challenging - sudokus. It's only one puzzle per page, with plenty of space in each square, which gives you plenty of room to use your ink pen without worrying about ending up with messy sudoku once you are finished.How much sharper will your mind be after you have solved these 100 sudoku puzzles?