Ответ:

  1. 889989 + 1 = 889990.
  2. 55283 − 50000 = 5283.
  3. 27836 + 2000 = 29836.
  4. 1000 − 1 = 999.
  5. 11100 : 100 = 111.
  6. 740 − (570 + 70) = 740 − 640 = 100.
  7. (456 − 7 * 8) : 10 = (456 − 56) : 10 = 400 : 10 = 40.
  8. 4912 * 100 = 491200.