Honestly, I haven't read it yet. After the book arrived I showed it to my daughter and she commented that her friend at school loves math. I suggested that she loan it to him. She did, and a couple days later she told me that he said to tell her dad "Thank you", because he is almost finished reading it and really loves it. I said, "Tell him to keep it or share it with others. I will order another." I haven't ordered its replacement yet, but will do it soon.