I know I've seen threads here containing recommended books for kids who want to read math books for fun, but I can't find them right now.
So ... if you have a 9 y/o bright math student who wants to ponder math concepts, what books would you get her? She takes Beast Academy with her for her bedtime reading. She's already read and loved the Penrose books. She has enjoyed Life of Fred.
Any favourites for me?