#include <bits/stdc++.h>
using namespace std;
bool desc(int a, int b) { return (a > b); }
bool pairone(pair<int, int> &a, pair<int, int> &b) {
  return (a.first < b.first);
}
void show(vector<int> vec) {
  for (auto x : vec) cout << x << " ";
  cout << endl;
  ;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    double sides = 2 * n;
    double side1 = 0;
    double theta0 = (180.0 * (sides - 2)) / (sides);
    double theta = 90 - theta0 / 2.0;
    int even = n / 2;
    int odd = n / 2 + 1;
    if (even % 2 == 1) swap(odd, even);
    int i;
    for (i = 0; i < even / 2; i++) {
      side1 += cos(theta * 3.14159265 / 180.00);
      theta = (180.0 - theta0 + theta);
    }
    side1 *= 2;
    side1 /= sqrt(2);
    theta = 180.0 - theta0;
    double side2 = 0;
    for (i = 0; i < (odd - 1) / 2; i++) {
      side2 += cos(theta * 3.14159265 / 180.0);
      theta = (180.0 + theta - theta0);
    }
    side2 += 0.5;
    side2 *= 2;
    side2 /= sqrt(2);
    double side = side1 + side2;
    cout << setprecision(15) << side << endl;
  }
}
