Charlie Piechart and the case of the missing hat

About this book

This math mystery takes place at school&#x;when a purple, sparkly cone-shaped princess hat goes missing! Margot needs her hat in time for the school play (today!), so Charlie and his dog companion, Watson, are on the case&#x;finding evidence of sparkles and purple paint and keeping on the lookout for geometric clues that might lead to the missing hat.