In this third in the series, Radius must prove himself on his quest for knighthood by rescuing a king. Sent off with the family medallion for luck, Radius dodges dangers and dragons. The ultimate challenge lies in a mysterious castle with a maze of many angles.
In this wonderfully illustrated series, go on math adventures with Sir Cumference, Lady Di of Ameter, and their son Radius. Each book presents a mathematical concept in such a way that it allows students to fully comprehend "how" and "why" the characters solve their unique problems.