\documentclass[a4paper,10pt]{article}
\usepackage{myXsim}

\author{Benjamin Bertrand}
\title{Logarithme et équation puissance - Cours}
\date{Janvier 2021}

\DeclareExerciseCollection{banque}
\xsimsetup{
    step=3,
}
\setlength{\columnseprule}{0pt}

\pagestyle{empty}
\geometry{left=10mm,right=10mm, top=5mm, bottom=10mm}
\setlength{\multicolsep}{6.0pt plus 2.0pt minus 1.5pt}

\begin{document}

\setcounter{exercise}{6}

\input{exercises.tex}
\printcollection{banque}
\vfill
\printcollection{banque}

\end{document}