To find the total number of cubes Louis has, we add the cubes in the two boxes:$$\textcolor{colordef}{1\,218} + \textcolor{colorprop}{1\,123}$$Using cubes, we can visualize the addition:
\(+\)
\(=\) 
This shows a total of \(\textcolor{colordef}{1\,218} + \textcolor{colorprop}{1\,123} = \textcolor{olive}{2\,341}\) cubes.
Counting each cube one by one would be tedious. Instead, we use column addition to calculate: