01 A work of fiction in which a character goes to a math class

[Evelyn]

I'm sure there are a lot of options for this, although I am having trouble coming up with titles in which I'm 100% sure a character goes to a math class. Here are a few I'm pretty sure would qualify. I'm interested in seeing what other people come up with!
Mean Girls
The Idiot
Annika Riz, Math Whiz
The Calculus of Murder

[Adam]

Divide Me By Zero - I'm reading this one now. The protagonist's mother writes math textbooks. One character mentions that he used to correct his high school math teacher, so that at least implies he went to a math class.

[Evelyn]

I'm laughing right now about how close Revenant Gun came to fulfilling this prompt without actually doing it. There's a character who has lost a lot of memories and needs to learn some remedial math but does so without going to a class, and at the end another character is about to start working as a math teacher, but we never see them actually go into a class!

[Alex]

The three books of “Math girls”, by Hiroshi Yuki. They are amazing, with actually good math and an interesting story.

[Colin]

I've just finished Math Girls -- it had me reaching for pencil and paper more than once :-) Very good mathematically (although I found the story a bit meh.)

Edit -- I read this as something not originally written in English, but I may decide to be flexible about that.