Basis Optellen

Reken uit

\(4 + 7 = \)

\(\begin{align} & 4 + 7 \\= & 7 + 4 \\= & 7 + \color{green}{3} + \color{red}{1} \\= & \color{green}{10} + \color{red}{1} \\= & \color{red}{11} \end{align}\)