Calcul (nombres naturels)

$$\begin{array}{rrrrrrr} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{}} & {\small\color{orange}{}}\\ & {\small\color{blue}{}} & {\small\color{blue}{}} & {\small\color{blue}{}} & {\small\color{blue}{2}} & {\small\color{blue}{1}} & {\small\color{blue}{}}\\ & {\small\color{red}{}} & {\small\color{red}{}} & {\small\color{red}{}} & {\small\color{red}{4}} & {\small\color{red}{2}} & {\small\color{red}{}}\\ & & & & & 8 & 5 & 1\\ \cdot & & & & & \color{orange}{1} & \color{blue}{3} & \color{red}{5}\\ \hline & & \color{red}{} & \color{red}{} & \color{red}{4} & \color{red}{2} & \color{red}{5} & \color{red}{5}\\ & & \color{blue}{} & \color{blue}{2} & \color{blue}{5} & \color{blue}{5} & \color{blue}{3} & \color{blue}{0}\\ + & & \color{orange}{} & \color{orange}{8} & \color{orange}{5} & \color{orange}{1} & \color{orange}{0} & \color{orange}{0}\\ \hline & & 1 & 1 & 4 & 8 & 8 & 5\\ \end{array}$$

Nouvel exemple