# Undefined control sequence when using \therefore [duplicate]

In my code I wrote :

 $\therefore$ There is a total of 21,168 ways that we can choose 2 chemists and 3 physicists.


However, I am getting the undefined control sequence error. I have used packages amsfonts and amsmath, but that doesn't seem to fix the problem.

Thank you.

You need to load amssymb:
\documentclass{article}
$\therefore$