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

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

int main() {
  double pi = 3.141592;
  int t;
  cin >> t;

  rep(i,t) {
    double r;
    cin >> r;
    cout << fixed << setprecision(10) << 3*sqrt(3)*r*r/4 << endl;
  }


}