\[\boxed{\text{61}\text{.}}\]
\[1)\ 12\ 143 \cdot 3 = 36\ 429\]
\[12\ 144 \cdot 4 = 48\ 576\]
\[12\ 145 \cdot 5 = 60\ 725\]
\[12\ 146 \cdot 6 = 72\ 876\]
\[12\ 147 \cdot 7 = 85\ 029\]
\[12\ 148 \cdot 8 = 97\ 184\]
\[12\ 149 \cdot 9 = 109\ 341\]
\[35\ 090 \cdot 9 = 315\ 810\]
\[35\ 080 \cdot 8 = 280\ 640\]
\[35\ 070 \cdot 7 = 245\ 490\]
\[35\ 060 \cdot 6 = 210\ 360\]
\[35\ 050 \cdot 5 = 175\ 250\]
\[35\ 040 \cdot 4 = 140\ 160\]
\[35\ 030 \cdot 3 = 105\ 090\]
\[2)\ 99\ 405\ :5 = 19\ 881\]
\[88\ 405\ :5 = 17\ 681\]
\[77\ 405\ :5 = 15\ 481\]
\[66\ 405\ :5 = 13\ 281\]
\[55\ 405\ :5 = 11\ 081\]
\[44\ 405\ :5 = 8\ 881\]
\[33\ 405\ :5 = 6\ 681\]
\[613\ 800\ :2 = 306\ 900\]
\[623\ 800\ :2 = 311\ 900\]
\[633\ 800\ :2 = 316\ 900\]
\[643\ 800\ :2 = 321\ 900\]
\[653\ 800\ :2 = 326\ 900\]
\[663\ 800\ :2 = 331\ 900\]
\[673\ 800\ :2 = 336\ 900\]