#include<stdio.h>
double sqrt(double x)
{
	double min, mid, max;
	min = 0;
	max = 1;
	while (max * max <= x)
		max *= 2;
	int i;
	for (i = 0; i < 500; i++)
	{
		mid = (max + min) / 2;
		if (mid * mid > x)
			max = mid;
		else
			min = mid;
	}
	return min;
}
int main()
{
	int t;
	scanf("%d", &t);
	double r;
	for (; t > 0; t--)
	{
		scanf("%lf", &r);
		printf("%.20lf\n", 3 * r * r * sqrt(3) / 4);
	}
	return 0;
}