Calcul (nombres naturels)

$$\begin{array}{rrrrrr} & {\small\color{red}{1}} & {\small\color{red}{}} & {\small\color{red}{1}} & {\small\color{red}{}} & {\small\color{red}{}}\\ & & 7 & 2 & 3 & 0\\ + & & 9 & 1 & 9 & 9\\ \hline & 1 & 6 & 4 & 2 & 9\\ \end{array}$$

Nouvel exemple