Ответ:\(30\,999 + 1 = 31\,000\).\(10\,000 - 1 = 9\,999\).\(25\,909 + 1 = 25\,910\).\(100\,000 - 1 = 99\,999\).\(39\,099 + 1 = 39\,100\).\(40\,000 - 1 = 39\,999\).\(699\,999 + 1 = 700\,000\).