1 * 9 + 2 = 11 12 * 9 + 3 = 111 123 * 9 + 4 = 1111 1234 * 9 + 5 = 11111 12345 * 9 + 6 = 111111 123456 * 9 + 7 = 1111111 1234567 * 9 + 8 = 11111111 12345678 * 9 + 9 = 111111111 123456789 * 9 + 10 = 1111111111