This list is was originally a list for a 6th grade teacher to use as read alouds and/or independent reading, but as I have worked on expanding it, it has grown to include books for older and younger students. I didn't include many picture books though there are tons of math picture books. I tried to stay with 4th and up.
Novels with Math Content
This list contains books that I recommended to her and have read as well as books that I added this week because of research and with the help of some friends on Twitter.
Uses math to describe human relationships and events
"Math whiz" friend, Geometry in pool, Gallileo
Theorems, Functions, Graphs
Protagonist with autism who is passionate about mathematics
Protagonist uses math in her everyday life
Mathematical instincts, Talented mathematician
A boy meets the number devil in his dreams and explores math with him
Nonfiction (Series) Math concepts, Math vocabulary
Codes, Fibonacci sequence
(Series) Protagonist with mathematical talents
(Series) Protagonist hates math
Characters with mathematical talents
(Series) Claudia struggles with math in all of the books, this one it is the focus
Mathematically talented boy looking for a math tutor to expand his knowledge
Fun math "problems"
Mathematical land filled with mathematical concepts and math history
Math equation is a clue in a murder