Too long eh?

$\LARGE{ \begin{array}{rlll} \phantom{0}\ \boxed{\color{#20A900}{3}} \ \boxed{\color{#20A900}{5}} \ \boxed{\color{#20A900}{7}} && \\[-4pt] \boxed{\color{#20A900}{1}} \ \boxed{3}\ \enclose{longdiv}{\boxed{\color{#20A900}{4}} \ \boxed{\color{#20A900}{6}} \ \boxed{\color{#20A900}{4}} \ \boxed{\color{#20A900}{1}} } && \\[-4pt] \underline{\boxed{\color{#20A900}{3}}\ \boxed{9}\, \phantom0 \phantom0 \phantom0 \phantom0} && \\[-4pt] \boxed{\color{#20A900}{7}} \ \boxed{\color{#20A900}{4}} \phantom0 \, \, \phantom0 && \\[-3pt] \underline{\boxed{\color{#20A900}{6}} \ \boxed{5} \,\, \phantom0 \phantom0 } && \\[-3pt] \boxed{\color{#20A900}{9}} \ \boxed{\color{#20A900}{1}} && \\[-2pt] \underline{\boxed{\color{#20A900}{9}} \ \boxed{1}} && \\[-2pt] \end{array} }$

Therefore, Sum of missing digits $\boxed{\color{#302B94}{70}}.$