Ответ:

  1. \(30\,999+1=31\,000\).
  2. \(10\,000-1=9\,999\).
  3. \(25\,909+1=25\,910\).
  4. \(100\,000-1=99\,999\).
  5. \(90\,100-1=90\,099\).
  6. \(40\,000-1=39\,999\).
  7. \(70\,099+1=70\,100\).
  8. \(699\,999+1=700\,000\).