\[\boxed{\mathbf{44}\mathbf{.}}\]
\[11 - 3 = 11 - 1 - 2 = 10 - 2 =\]
\[= 8\]
\[12 - 6 = 12 - 2 - 4 = 10 - 4 =\]
\[= 6\]
\[13 - 4 = 13 - 3 - 1 = 10 - 1 =\]
\[= 9\]
\[14 - 5 = 14 - 4 - 1 = 10 - 1 =\]
\[= 9\]
\[12 - 7 = 12 - 2 - 5 = 10 - 5 =\]
\[= 5\]
\[11 - 9 = 11 - 1 - 8 = 10 - 8 =\]
\[= 2\]
\[14 - 6 = 14 - 4 - 2 = 10 - 2 =\]
\[= 8\]
\[16 - 8 = 16 - 6 - 2 = 10 - 2 =\]
\[= 8\]
\[13 - 8 = 13 - 3 - 5 = 10 - 5 =\]
\[= 5\]
\[15 - 6 = 15 - 5 - 1 = 10 - 1 =\]
\[= 9\]
\[17 - 9 = 17 - 7 - 2 = 10 - 2 =\]
\[= 8\]
\[18 - 9 = 18 - 8 - 1 = 10 - 1 =\]
\[= 9\]