Xlop (eXtra Large OPeration) will typeset arithmetic problems either in-line or “as in school” (using French school conventions). So for example, \opadd{2}{3} can give either $2+3=5$ or something similar to: \begin{tabular}{r} 2\\ +3\\ \hline 5\end{tabular}.

Furthermore, numbers may be very large, e.g 200 figures (with a very long compilation time). Many other features allow to deal with numbers (tests, display, some high level operations, etc.)