Ответ:

  1. \(999+1=1000\)
  2. \(700+80+9=789\)
  3. \(34-7-40=27-40=-13\)
  4. \(570+30-330=600-330=270\)
  5. \(900-1=899\)
  6. \(960+50-660=1010-660=350\)

Ответ: 1000; 789; −13; 270; 899; 350.