Calcul (nombres naturels)

$$\begin{array}{rrrrrrr} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{1}}\\ & {\small\color{blue}{}} & {\small\color{blue}{}} & {\small\color{blue}{}} & {\small\color{blue}{1}} & {\small\color{blue}{2}}\\ & {\small\color{red}{}} & {\small\color{red}{}} & {\small\color{red}{}} & {\small\color{red}{1}} & {\small\color{red}{2}}\\ & & & & 1 & 2 & 4\\ \cdot & & & & \color{orange}{3} & \color{blue}{7} & \color{red}{6}\\ \hline & & \color{red}{} & \color{red}{} & \color{red}{7} & \color{red}{4} & \color{red}{4}\\ & & \color{blue}{} & \color{blue}{8} & \color{blue}{6} & \color{blue}{8} & \color{blue}{0}\\ + & & \color{orange}{3} & \color{orange}{7} & \color{orange}{2} & \color{orange}{0} & \color{orange}{0}\\ \hline & & 4 & 6 & 6 & 2 & 4\\ \end{array}$$

Nouvel exemple