See the code:

```
\documentclass{scrartcl}
\usepackage[per-mode = fraction]{siunitx}
\begin{document}
  Text. \numrange{1}{3} experiments.\\[\baselineskip]
  Text. \SIrange{1}{5}{\kg} text.\\[\baselineskip]
  Text. $k = \numrange{1}{3}$ experiments text.\\[\baselineskip]
  Text. $v = \SIrange{1}{5}{\cubic\m\per\kg}$ text.\\[\baselineskip]
\end{document}

```

And the result:

[![result](https://i.stack.imgur.com/3dpdu.png)](https://i.stack.imgur.com/3dpdu.png)

In text mode it works properly. But in math mode there is no space before and after *to* and it has italic shape. Why is it so? What do I wrong?

Thank you for your help and effort in advance!