using System;

class Program
{
    static void Main()
    {
        int t = int.Parse(Console.ReadLine());
        for (int i = 0; i < t; i++)
        {
            double r = double.Parse(Console.ReadLine());
            double area = 3 * Math.Sqrt(3) / 4 * r * r;
            Console.WriteLine(area.ToString("F12"));
        }
    }
}