\[\boxed{\mathbf{497.}}\]
\[42 \cdot 2 = 84\]
\[42\ :2 = 21\]
\[400\ :2 = 200\]
\[400 \cdot 2 = 800\]
\[220\ :2 = 110\]
\[220 \cdot 2 = 440\]