Ответ:

  1. \(966\cdot37=966\cdot(40-3)=38\,640-2\,898=35\,742\).
  2. \(307\cdot14=307\cdot(10+4)=3\,070+1\,228=4\,298\).
  3. \(689\cdot820=689\cdot82\cdot10=(55\,120+1\,378)\cdot10=564\,980\).
  4. \(8\,599\cdot91=8\,599\cdot(100-9)=859\,900-77\,391=782\,509\).
  5. \(9\,006\cdot86=9\,006\cdot(80+6)=720\,480+54\,036=774\,516\).