\starttext

\startMPcode
    fill fullcircle scaled 3cm ;
    if known numbersystem :
        draw textext(numbersystem) withcolor white ;
    fi
\stopMPcode

\blank

\startMPcode{doublefun}
    fill fullcircle scaled 1e1 cm ;
    if known numbersystem :
        draw textext(numbersystem) withcolor white ;
    fi
\stopMPcode

\stoptext
