- The appendix isn't even written by John Green—he asked his friend, Daniel Biss, to write it about the math in the book. It unpacks what happens in Colin's Theorem of Underlying Katherine Predictability, using math.
- There's a bunch of graphs, a lot of formulas, and a whole lot of math behind what Colin works on.
- Check it out if you're in to that sort of thing. We'll just take Biss's word for it.