using System;

public class Program

{

    public static void Main()

    {

        double testNumber = 5;

        Console.WriteLine(testNumber.Pow(2));

    }

}

​

static public class MyExtensionMethods

{

    static public double Pow(this double source, double power)

    {

        return Math.Pow(source, power);

    }

    static public double ToRadians(this double source)

    {

        return source * Math.PI / 180;

    }

}