operators within the dollar sign

Question

I am using operators : +,-. For example, $6-1$. The operator - becomes rather large between $ $.

Normally, would you leave the operator negative between the $$? If not, how do you make it to the normal size ?

Answer 1

Since you're referring to - in the mathematical context, use it as such in (La)TeX. So, use $-i$ instead of -$i$. Use $k+p$ instead of $k$+$p$. Here are some examples of the output:

\documentclass{article}
\begin{document}
If I use -$i$, the spacing around the symbol and operator is not correct. 
Compare this to $-i$. 
Also, when using these operators in a binary sense, it should be used as $k+p$, and not $k$+$p$.

\begin{center}
  \begin{tabular}{cc}
    Wrong & Correct \\ \hline
    -$i$ & $-i$ \\
    $k$+$p$ & $k+p$
  \end{tabular}
\end{center}
\end{document}