using System;

using System.Text.RegularExpressions;

public static class Program

{

    public static void Main()

    {

        int n;

        bool isNumeric = int.TryParse("11", out n);

        Console.WriteLine(isNumeric);

        //using Regular Expression

        var RegexCheck=Regex.IsMatch("11", @"^\d+$");

        Console.WriteLine(RegexCheck);

        //Using Custom Method

        Console.WriteLine(IsNumeric("Test"));

        Console.WriteLine(IsNumeric("11.3"));

    }

    public static bool IsNumeric(this string s)

    {

        float output;

        return float.TryParse(s, out output);

    }

}