\documentclass[a4paper,10pt]{letter}
\usepackage[utf8]{inputenc}
\usepackage{siunitx}
%opening
\title{latexdiff test of siunitx}

\begin{document}
\num{10}

\numlist{10;12;14}

\numproduct{10x12}

\numrange{5}{10}

\ang{3}

\unit{\cm}

\qty{20}{\cm}

\qtylist{10;20;30}{\cm}

\qtyproduct{10x12}{\square\cm}

\qtyrange{10}{12}{\cm}

\complexnum{10+2i}

\complexqty{10+2i}{\cm}

\num[round-mode=places, round-precision=2, exponent-mode=scientific]{987654321}


\end{document}