import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        for (int i = 0; i < t; i++) {
            int r = sc.nextInt();
            System.out.println(3 * Math.sqrt(3) * r * r / 4);
        }
    }
}