(a) 78,921,092 = Seventy-eight million nine hundred twenty-one thousand ninety-two
(b) 7,452,483 = Seven million four hundred fifty-two thousand two hundred eighty-three
(c) 99,985,102 = Ninety-nine million nine hundred eighty-five thousand one hundred two
(d) 48,049,831 = Forty-eight million forty-nine thousand eight hundred thirty-one