a) 1112 = 1 * 22 + 1 * 21 + 1 * 20 = 4 + 2 + 1 = 7
б) 10102 = 1 * 23 + 0 * 22 + 1 * 21 + 0 * 20 = 8 + 0 + 2 + 0 = 10
в) 110112 = 1 * 24 + 1 * 23 + 0 * 22 + 1 * 21 + 1 * 20 = 16 + 8 + 0 + 2 + 1 = 27