\[\boxed{\mathbf{12.}}\]
\[40 - 3 = 37\]
\[40 - 13 = 27\]
\[40 - 23 = 17\]
\[40 - 33 = 7\]
\[50 - 2 = 48\]
\[50 - 12 = 38\]
\[50 - 22 = 28\]
\[50 - 32 = 18\]
\[60 - 4 = 56\]
\[60 - 14 = 46\]
\[60 - 24 = 36\]
\[60 - 34 = 26\]
\[70 - 6 = 64\]
\[70 - 16 = 54\]
\[70 - 26 = 44\]
\[70 - 36 = 34\]