All kinds of fun and thought-provoking problems, including mazes, magic numbers, mixed-up pictures and brain teasers. Some of the puzzles are quite easy, others will probably make you think a bit. There are clues near the end of each book to help you with some of the more difficult puzzles. These give a hint without telling you the answer and spoiling the fun. There are, of course, answers to all the puzzles at the end of the book.