Math nerds & teachers/teacher-adjacent friends, seeking recommendations! My nephew (7) loves math & has quite a gift for it. He’s figured out square numbers on his own. I’d like to find some books to encourage his exploration and discovery around math. I know about Martin Gardner’s books but worry they might be above his reading level. Did Martin Gardner ever write books targeted to children? Are there other books/authors I should look at? I’m down for any/all recommendations! #math