Although this question is very simple in the substance, I would like to ask it anyway. Visibly if I use the comma within the mathematical environment you can see a small space that I have underlined with a red horizontal line.
%% Compile and read me!
\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\begin{document}
\[a=(3,15 \pm 0,22) \text{ cm}\]
\end{document}
Surely the space, with the use of siunitx package it will disappear as it is a specific package for units and decimal numbers. To remove this space I use the command to have a negative space \!. In fact I obtain this:
\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\begin{document}
\[a=(3,\!15 \pm 0,\!22) \text{ cm}\]
\end{document}
Are there any other alternatives without the use of siunitx package? Are there possible contraindications if you do not use this package?


\num{3e-2}instead of3 \cdot 10^{-3}and with the former it is even possible to combin all exponents of 10 to a single one … and for errors you can use the short syntax3,15(22)and have it printed as in your example. – Tobi Feb 07 '20 at 22:06siunitxmyself...however, the problem here, I think, is independent of that package, and is related to the fact that,is of math category\mathpunct. – Steven B. Segletes Feb 07 '20 at 22:06icommapackage to change the default mode of commas frommath-puncttomath-ord. To restore the math-punct behavior of commas, just leave a space after them. E.g., change$[0,1]$to$[0, 1]$to typeset the interval with an appropriate amount of whitespace after the comma. – Mico Feb 07 '20 at 22:06siunitxseems much shorter, thus faster … in my editor I have a keyboard shortcut for\numand\SIso these are only on “click” away and then I just have to enter the numbers. (I wrote a blog post about this some time ago: https://tobiw.de/tbdm/siunitx but it is in German …) – Tobi Feb 08 '20 at 11:15