 \documentclass[12pt]{beamer}
 \usepackage[frenchb]{babel}
 \usepackage{aeguill}
 \usepackage{xlop,multido,calc
}
 \usepackage{xcolor}
 \newcommand{\blanc}{\textcolor{white}}
 \newcommand{\noir}{\textcolor{black}}
 \newcommand{\rouge}{\textcolor{red}}

\newcounter{ret}

\makeatletter
\newcounter{nbtoken}
\newcommand\CountToken[1]{%
  \setcounter{nbtoken}{0}%
  \C@untToken#1\@nil
}
\newcommand\C@untToken{%
  \afterassignment\C@untT@ken\let\CurrT@ken=
}
\newcommand\C@untT@ken{%
  \ifx\CurrT@ken\@nil \else
    \stepcounter{nbtoken}%
    \expandafter\C@untToken
  \fi
}
\makeatother





\newcommand{\frameop}[2]{%
\CountToken{#1}
\begin{frame}
  \Huge
  \opset{decimalsepsymbol={,},columnwidth=2ex,lineheight=\baselineskip}%
  \begin{center}
  \only<+>{\opadd[resultstyle=\blanc,carrystyle=\small\blanc]%%
    {#1}{#2}}%% %%
  \only<+>{\opadd[resultstyle=\blanc,carrystyle=\small\blanc,deletezero=false]%%
    {#1}{#2}}%% %%
\multido{\i=1+1}{\thenbtoken}{%
\setcounter{ret}{\i+1}
\only<+>{\opadd[resultstyle=\blanc,deletezero=false,carrystyle=\small\blanc,%%
    operandstyle.1.\i=\rouge,operandstyle.2.\i=\rouge,carrystyle.\i =\small\rouge]%%
    {#1}{#2}}%% %%
\only<+>{\opadd[resultstyle=\blanc,deletezero=false,carrystyle=\small\blanc,%%
    carrystyle.\theret =\small\rouge , carrystyle.\i =\small\rouge,
    operandstyle.1.\i=\rouge,operandstyle.2.\i=\rouge,resultstyle.\i=\rouge]%%
    {#1}{#2}}%% %%
}
\only<+>{\opadd[carrystyle=\small,deletezero=false]{#1}{#2}}%%
\end{center}
\end{frame}
}







 \begin{document}
 

\frameop{1234567}{89101}


 \end{document}