\[\boxed{\mathbf{2.}}\]
\[1)\ a = 27 \cdot 31 + 23 =\]
\[= 837 + 23 = 860\]
\[a = 860.\]
\[2)\ a = 36 \cdot 43 + 17 =\]
\[= 1548 + 17 = 1565\]
\[a = 1565.\]