The answer to this question is inevitably font specific, but within a given font (and you'll have to hand adjust the metrics for each typeface), this approach should work. I have used only relative lengths (ie ex
and em
) which means that the approach scales, and used ulem
instead of stacking like the other answer, mainly because it allows for easier adjustment of the thickness of the line to fit the glyph of the typeface in question. The example below isn't perfect, but is at least workable for most cases (and there is frankly an effort/reward question for how precisely the s
aligns with the rest of the glyph). The following works for Minion Pro at any size and for all weights/fonts (bold, italic, etc), and the approach taken should, in theory, allow for any font's glyph to be pluralized (after unfortunately painstaking adjustments):
\documentclass{article}
\usepackage[paperwidth=0.35in,paperheight=1.25in]{geometry}
\usepackage[normalem]{ulem}
\renewcommand{\ULdepth}{.375ex}
\renewcommand{\ULthickness}{.07em}
\usepackage{graphicx}
\newcommand{\numeros}{№\kern -.7ex\raisebox{.525ex}{\scalebox{.65}{\uline{\hskip 1ex s}}}}
\usepackage{fontspec}
\setmainfont{Minion Pro}
\begin{document}\pagestyle{empty}
\centering\numeros\\\large\numeros\\\itshape\numeros\\\bfseries\numeros
\end{document}