#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int t;
  cin >> t;
  while (t--) {
    int r;
    cin >> r;
    double ans = r * r * 0.25 * sqrt(3) * 3;
    cout << fixed << setprecision(10) << ans << endl;
  }
  return 0;
}