using System;
using System.Collections.Generic;
using static System.Console;
using System.Linq;

class yuki
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static void Main()
    {
        var t = NN;
        for (var i = 0; i < t; ++i)
        {
            var r = NN;
            WriteLine(r * r * Math.Sqrt(3) * 3 / 4);
        }
    }
}