My flashcard with \forloop is working after your help.
I try it with \foreach (tikz) but it's not working.
The pdf files contain only one flash card in the bottom right corner, the 24th card and the 48th,...
The minimal non-working example is :
\documentclass{flacards}
\usepackage[frenchb]{babel}
\usepackage{tikz}
\begin{document}
\foreach \x in {1,2,...,50}{\card{a}{b}}
\end{document}
but the \forloop version is working :
\documentclass{flacards}
\usepackage[frenchb]{babel}
\usepackage{forloop}
\begin{document}
\newcounter{compteura}
\forloop{compteura}{1}{\value{compteura} < 11}{\card{a}{b}}
\end{document}
I prefer use tikz for the math possibility.
Until such time I use package calc for doing math on counter.