\[\boxed{\mathbf{12.}}\]
\[1)\ 35,\ 21,\ 14,\ 42,\ 63,\ 56,\ 70,\ 28,\ 49.\]
\[2)\ 35\ :7 = 5\]
\[21\ :7 = 3\]
\[14\ :7 = 2\]
\[42\ :7 = 6\]
\[63\ :7 = 9\]
\[56\ :7 = 8\]
\[70\ :7 = 10\]
\[28\ :7 = 4\]
\[49\ :7 = 7\]