I got time out error too in C#. Resolved it only by adding this code: int result = 0; string rev = ""; int dif = 0; int revNum = 0; for (int n = i; n < j + 1; n++) { if (j > k) { dif = n; rev = ""; while (dif >= 10) { rev = rev + (dif % 10).ToString(); dif = dif / 10; } rev = rev + dif.ToString();

                if (rev == n.ToString())
                {
                    result++;
                }
                else
                {
                    revNum = Convert.ToInt32(rev);
                    if ((n - revNum) % k == 0) result++;
                }

            }
            else
            {
                var poly = n.ToString();
                if (poly.Length == 1) result++;
                for (int l = 0; l < poly.Length / 2; l++)
                {
                    if (poly[l] != poly[poly.Length - l - 1])
                    {
                        break;
                    }
                    if (l + 1 == poly.Length / 2)
                    {
                        result++;
                    }
                }
            }
        }

        return result;