You can insert LaTeX/KaTeX equations into your notes.
This page shows the supported functions and symbols you can display with KaTeX.
Tip: Use an online LaTeX equation editor, such as this one from TutorialsPoint, that lets you visually design your equations before you paste it into Codex.
To insert an in-line equation, type a $ symbol, followed by your LaTeX statement, then another $. The equation should automatically render. You can also click the equation or move your cursor back into it to edit.
To insert a block-level equation, go onto a new empty line and type $$ and hit Space Then you can type in your KaTeX formula.