[Tex/LaTex] siunitx and missing decimal point

Question

\si seems to be not showing decimal points, unless I specifically specify \num.

\documentclass[12pt]{report}
\usepackage{siunitx}

\begin{document}
\si{12.5\milli\gram}

\si{\num{12.5}\milli\gram}
\end{document}

Is this expected behavior?

Answer 1

The command \si{units} is for units only. You have to use the \SI{number}{units} for what you want to do.