This book is full of interesting and enticing math knowledge, problems, history. I recommend it, we all had fun this morning trying to solve some of the riddles. Then Blue Heart made a riddle, "if you are in a room full of snakes and you try to cross to the other side where the door is, how can you do it?" "Easy, you just step on the snakes". (I think she remembered My Father's Dragon where Elmer steps on the crocodiles, granted they were busy eating a lolly pop tied at the tail of the crocodile in front of the line).