\[\boxed{\mathbf{3.421}}\]
\[\textbf{а)}\ (98 \cdot 6 + 105)\ :63 = 11\]
\[1)\ 98 \cdot 6 = (100 - 2) \cdot 6 =\]
\[= 600 - 12 = 588\]
\[2)\ 588 + 105 = 693\]
\[3)\ 693\ :63 = (630 + 63)\ :63 =\]
\[= 10 + 1 = 11\]
\[\textbf{б)}\ 4 \cdot (356 - 456\ :8) = 1196\]
\[1)\ 456\ :8 = (400 + 56)\ :8 =\]
\[= 50 + 7 = 57\]
\[2)\ 356 - 57 = 299\]
\[3)\ 299 \cdot 4 = (300 - 1) \cdot 4 =\]
\[= 1200 - 4 = 1196\]
\[1)\ 390\ :15 = 26\]
\[2)\ 32 - 26 = 6\]
\[3)\ 5632\ :512 = 11\]
\[4)\ 4256\ :38 = 112\]
\[5)\ 11 + 112 - 6 = 117\]
\[1)\ 3 \cdot 504 = 1512\]
\[2)\ 4 \cdot 307 = 1228\]
\[3)\ 1512 - 1228 = 284\]
\[4)\ 3124\ :284 = 11\]
\[5)\ 10\ 403\ :101 = 103\]
\[6)\ 11 + 103 = 114\]