using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ProgrammingExamples
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create a constant fixed value like this
            const double PI = 3.142;

            // Declaring variables
            double areaOfCircle;
            double radius;

            // Set the value for the radius
            radius = 4.3;

            // Calculate the area of a circle
            // Radius squared = r x r
            // Area = PI x Radius squared

            areaOfCircle = PI * (radius * radius);  // Result is 58.09
        }
    }
}