Is it possible to get the current item number and perform arithmetic on it in enumerate environment?

Question

That is, suppose that I am at item n and I want to make a reference to item n - 3 without explicitly specifying it.

Answer 1

How about

    \item \number\numexpr\value{enumi}-3\relax

Here's a complete MWE:

\documentclass{article}

\begin{document}

\begin{enumerate}
    \item cow
    \item lion
    \item moo
    \item \number\numexpr\value{enumi}-3\relax
    \item meow
\end{enumerate}
\end{document}