#include <bits/stdc++.h>
using namespace std;

void solve() {
	int r;
	cin >> r;
	cout << r * r * sin(M_PI / 3) * 3 / 2 << endl;
}

int main() {
	cout << fixed << setprecision(10);
	int t;
	cin >> t;
	while(t--) solve();
}