15 = 1, 3, 5, 15 21 = 1, 3, 7, 21 28 = 1, 2, 4, 7, 14, 28 48 = 1, 2, 3, 4, 6, 8, 12, 16, 24, 48 100 = 1, 2, 4, 5, 10, 20, 25, 50, 100