My mom got me this book a few days ago. I'veonly done 10 out of the 21 puzzles, but I feelthat it challenges me well, and it is a good book.There is one problem though. Puzzle #7 doesn'twork out. I even looked at the answer, and it stilldoesn't work. They're trying to say that 33x38=912,when it actually equalls 1254. My mom and I areboth quite upset about this, but the quality of theother problems nearly makes up for this flaw.