subfigure- what do do with whitespace

Question

So I've made a block of figures using the subcaption package. It contains 5 images and follows the following layout:

\begin{figure}[t]
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {1.pdf}
                \caption{$1$}
                \label{fig:1}
        \end{subfigure}
        ~
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {2.pdf}
                \caption{$2$}
                \label{fig:2}
        \end{subfigure}
        ~
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {3.pdf}
                \caption{$3$}
                \label{fig:3}
        \end{subfigure}
        ~
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {4.pdf}
                \caption{$4$}
                \label{fig:4}
        \end{subfigure}
        ~
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {5.pdf}
                \caption{$5$}
                \label{fig:5}
        \end{subfigure}
        ~  

        \caption{Plots of numbers.}
        \label{fig:numbers} 

\end{figure}

My question is: what should I do with the whitespace? I thought of either putting the figure caption there, or centering the last two images so the whitespace is symmetrical. However I don't how to do any of the two. For the latter, I tried inserting an extra ~ before the fourth image but it didn't work-nothing happened.

Answer 1

Please always post complete documents (I had to ask in chat which package you were using as my guess of subfigure proved wrong).

The image shows two layouts: the second one from the code as posted to get the first just simply use \hfill in all cases not the blank line and \hfil construct.

\documentclass{article}

\usepackage{subcaption}

\usepackage[demo]{graphicx}

\begin{document}

\begin{figure}[t]
\centering
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {1.pdf}
                \caption{$1$}
                \label{fig:1}
        \end{subfigure}%
        \hfill
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {2.pdf}
                \caption{$2$}
                \label{fig:2}
        \end{subfigure}%
        \hfill
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {3.pdf}
                \caption{$3$}
                \label{fig:3}
        \end{subfigure}%

        \mbox{}\hfil%
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {4.pdf}
                \caption{$4$}
                \label{fig:4}
        \end{subfigure}%
        \hfil
        \begin{subfigure}[t]{0.3\textwidth}
                \includegraphics[width=\textwidth]
                {5.pdf}
                \caption{$5$}
                \label{fig:5}
        \end{subfigure}


        \caption{Plots of numbers.}
        \label{fig:numbers} 

\end{figure}

\end{document}