(check(k.ToString() == 1)) : <p>I have a maybe simple problem. When i start program it show "Operator '==' cannot be applied to operands of type 'string' and 'int'. I dont know what to do with it. Thanks for every help.
Here is code: </p>

<pre><code>    class Program

{


    static bool check(string input_number)
    {
        for (int i = 0; i &lt; input_number.Length / 2; i++)
            if (input_number[i] != input_number[input_number.Length - i - 1])
                return false;
        return true;
    }



    static void Main(string[] args)
    {
        var results = from i in Enumerable.Range(100, 900)
                      from j in Enumerable.Range(i, 1000 - i)
                      let k = i * j
                      where (check(k.ToString() == 1)
                 orderby k descending
                      select new { i, j, k };
        var highestResult = results.FirstOrDefault();

        if (highestResult == null)
            Console.WriteLine("There are no palindromes!");
        else
            Console.WriteLine($"The highest palindrome is {highestResult.i} * {highestResult.j} = {highestResult.k}");
        Console.ReadKey();
    }
}
</code></pre>
