4 ways to framed displayed formulas in LaTeX

This article will show on how to display formulas (mathematics equations) inside a box or frame.

Using fbox and parbox

The formula will be framed. Must declare the width of the frame.

\fbox {
    \parbox{5cm} {
     [
     \oint\limits_C V,d\tau =
     \oint\limits_\Sigma \nabla \times V,d\sigma
     ]
    }
}

Using fbox and minipage

The formula will be framed. Must declare the width of the frame.

\fbox {
    \begin{minipage}[position]{5cm}
    [
     \oint\limits_C V,d\tau =
     \oint\limits_\Sigma \nabla \times V,d\sigma
    ]
    \end{minipage}
}

Using equation environment and fbox

The formula will be centred, framed and numbered.

\begin{equation}
\fbox {
    $ \displaystyle \oint\limits_C V,d\tau =
     \oint\limits_\Sigma \nabla \times V,d\sigma $
}
\end{equation}

Using displaymath enviroment and fbox

The formula will be centred, framed and unnumbered.

\begin{displaymath}
\fbox {
    $ \displaystyle \oint\limits_C V,d\tau =
    \oint\limits_\Sigma \nabla \times V,d\sigma $
}
\end{displaymath}