\documentclass{article}
\usepackage{latexml}
\usepackage{amsmath}
\begin{document}

% just a sequence of two numbers
$1,2$

% a list of monomials
$2x, 4y, 6z$

% a list of variables, one of which having a dependent modifier (equality)
$a=b,c,d$

% a list of numbers, one of which having a dependent modifier (less-than)
$1<2,3$

% a slightly longer list of numbers, one of which having a dependent modifier (less-than)
$1<2,3,4$

% a sequence of formulas
$1+2=3 , 3+4=7$

% a sequence of sigils, usually for notational purposes
$+,-,\times$
$+,-,\times .$
$+,G$

\end{document}