\ProvidesPackage{bengalidigits}
  [2015/05/25 v.01%
   Formatting of Bengali digits]

\def\bengalidigits#1{\expandafter\@bengali@digits #1@}
\def\@bengali@digits#1{%
  \ifx @#1% terminate
  \else
    \ifx0#1০\else\ifx1#1১\else\ifx2#1২\else\ifx3#1৩\else\ifx4#1৪\else\ifx5#1৫\else\ifx6#1৬\else\ifx7#1৭\else\ifx8#1৮\else\ifx9#1৯\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi
    \expandafter\@bengali@digits
  \fi
}
\endinput