using static System.Console;
using static System.Math;
 
public class Test {
	public static void Main() {
		WriteLine($"O valor de PI é: {Round(Calculadora.PI, 4)}");
		WriteLine($"A área é: {Calculadora.CalculaAreaCircunferencia(2):0.####}");
	}
}
 
public class Calculadora {
    public static double PI = System.Math.PI;
    public static double CalculaAreaCircunferencia(double raio) => PI * Pow(raio, 2);
}
 
//https://pt.stackoverflow.com/q/571427/101

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