When young Per visits her uncle Sir Cumference and his family, she learns how to play the game, "Inners and Edges." After she finds a clue linking the game to the mysterious castle on the island of Immeter, she must figure out how to find the perimeter and area of a circle to unlock the island's secret.
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.