$${\mathtt{4.23}}{m}{\mathtt{\,\small\textbf+\,}}{\mathtt{1.99}}{m}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{m} = {\mathtt{8.22}}{m}$$
http://www.frustfrei-lernen.de/mathematik/groessen-umrechnen.html
$${\mathtt{4.23}}{m}{\mathtt{\,\small\textbf+\,}}{\mathtt{1.99}}{m}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{m} = {\mathtt{8.22}}{m}$$
http://www.frustfrei-lernen.de/mathematik/groessen-umrechnen.html