How do I find the following error from running latex on my .tex file?

! Missing $ inserted.
<inserted text> 
                $
l.6   \item
            $<$, less than, 13
? x

By looking at my .ind file I find the following:

  \item !, shebang, 7
  \item !=, not equal, 13
  \item $, \${29}
  \item $<$, less than, 13

If I remove "\item $, \${29}" from the .ind file the .dvi file is produced without apparent problems. I have searched the .tex file line by line but cannot find the errant missing $. What does {29} refer to? The .dvi output page?

Update: Fixed closing <p> tags and updated title, per Consideration. (footpad, 24 Sep 2019)