[Tex/LaTex] How to write modulo relation in math mode

Question

I am trying to type the expression below:

From latex math symbols I searched for on the web, I tried:

$(m^k)^u \equiv m \mod{pq}$

but the 'mod' won't show up.
So I have again tried without the curly brackets:

$(m^k)^u \equiv m \mod pq$

but this, too, doesn't seem to work.

What am I doing wrong?

Answer 1

As a comment of excellent user Bernard I have provide to add a code and also with \pod{pq}.

\documentclass[a4paper,12pt]{article}
\usepackage{mathtools}
\begin{document}

\begin{align*}
  (m^k)^u &\equiv m \mod{pq}\\
  (m^k)^u &\equiv m \pmod{pq} \\
  (m^k)^u &\equiv m \;\mathrm{mod}\; pq\\
  (m^k)^u &\equiv m \pod{pq}
\end{align*}
\end{document}