\[\boxed{\mathbf{8.}}\]
\[2 \cdot 3 = 6\]
\[3 \cdot 2 = 6\]
\[6\ :3 = 2\]
\[6\ :2 = 3\]
\[4 \cdot 2 = 8\]
\[2 \cdot 4 = 8\]
\[8\ :2 = 4\]
\[8\ :4 = 2\]
\[5 \cdot 2 = 10\]
\[2 \cdot 5 = 10\]
\[10\ :2 = 5\]
\[10\ :5 = 2\]
\[6 \cdot 2 = 12\]
\[2 \cdot 6 = 12\]
\[12\ :2 = 6\]
\[12\ :6 = 2\]