\[\boxed{\mathbf{473.}}\]
\[21 \cdot 3 = 63\]
\[1)\ 21 = 30 + 1\]
\[2)\ 20 \cdot 3 = 60\]
\[3)\ 1 \cdot 3 = 3\]
\[4)\ 60 + 3 = 63\]
\[Проверка:\]
\[21 + 21 + 21 = 63.\]