Basis Optellen

Reken uit

\(47 + 30 = \ldots\)

\(\begin{align} & 47 + 30 \\ = & 30 + 47 \\= & 30 + \color{green}{40} + \color{red}{7} \\ = & \color{green}{70} + \color{red}{7} \\ = & \color{red}{77} \end{align}\)