#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <queue>
#include <map>
#include <cmath>
#include <iomanip>

using namespace std;

const long long MOD = (long long)(1e9) + 7;

int main() {

  cout << fixed << setprecision(15);

  int t;
  cin >> t;
  while (t--) {
    long double r;
    cin >> r;
    long double ans = 3 * sqrt(3) * r * r / 4;
    cout << ans << endl;
  }
  
  return 0;
}