\[\boxed{\mathbf{2}\mathbf{.}\mathbf{197}}\]
\[\textbf{а)}\ 806\ :31 + 23 \cdot 17 =\]
\[= 26 + 391 = 417\]
\[\textbf{б)}\ (2597 + 4102)\ :231 + 699 =\]
\[= 29 + 699 = 728\]
\[\textbf{в)}\ 43 \cdot 11 + 51 \cdot 15 = 1238\]
\[\textbf{г)}\ (318 - 263) \cdot 31 - 65 =\]
\[= 55 \cdot 31 - 65 = 1705 - 65 =\]
\[= 1640\]