Method returning different value types from the same class

I just started learning C#. I would like the Calculate method to be able to return objects of different types from Result class but I receive "Error CS0029 Cannot implicitly convert type ‘string’ to ‘Calculator.Backend.Result’" and "Error CS0029 Cannot implicitly convert type ‘int’ to ‘Calculator.Backend.Result’". I understand what they mean but I have no idea how am I supposed to solve these problems. Thank you for help in advance and sorry if my question is too basic.

public class Result
{
    public string Message = "Test";
    public int Value;
}
 public class Calculator
{
    public Result Calculate(string request)
    {
        Result Message = new Result();

        if (request == null)
        {   
            return Message.Message;
        }
        else
        {
            return Message.Value;
        }
    }
}

>Solution :

My psychic debugging powers are telling me that you want to display int when the result of the calculation is a number, and you want to display a string with an error message when there is an error performing the calculation.

If that’s the case, I’d probably just return the whole message as a Result, and then where you’re actually showing output, just use a string:

Console.WriteLine("Result: {0}", 
    string.IsNullOrEmpty(result.Message) ? result.Value.ToString() : result.Message);