\setupmathematics
  [autopunctuation=yes]

\starttext

    \startTEXpage[offset=10pt]
        $    1.2 \quad    1,2 \quad    1.2 \quad    1,2 $\par
        $\mn{1.2}\quad\mn{1,2}\quad\mn{1.2}\quad\mn{1,2}$
    \stopTEXpage

\stoptext
