Mark Dain My cryptography notes are written in plaintext, which is fine for me, but it seems to break down the moment I try to write any equations out. Is it worth learning LaTeX? I think Pages can't handle these sorts of equations.

Martijn Yes, learning a subset of (La)TeX for math is certainly worth it. I use it all the time in Uni to write down equations with nested division etc. Several Markdown editors are able to render it thanks to MathJax, which is great! Write in plaintext and use a math-enabled Markdown viewer to see the equations when reading.

Eric Why not pen and paper? Saves learning another language (or is that notation which is the correct word?)