Help pls

Question

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

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
const double pi = 3.14;
double radius;
string r;
r= Console.ReadLine();
Console.WriteLine(pi* (r* r));
//your code goes here

}
}
}

Answer 1

your variable r should be double .

double r;
r = Convert.ToDouble(Console.ReadLine());

Answer 2

Thx