\[\boxed{\mathbf{441.}}\]
\[2 \cdot 8 = 16\]
\[3 \cdot 9 = 27\]
\[4 \cdot 7 = 28\]
\[6 \cdot 3 = 18\]
\[6 \cdot 6 = 36\]
\[7 \cdot 5 = 35\]
\[7 \cdot 3 = 21\]
\[8 \cdot 7 = 56\]
\[9 \cdot 4 = 36\]
\[6 \cdot 9 = 54\]