#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vl>;
using vd = vector<double>;
const ll delta = 0.0000001;
const ll INF = 1e18 + 7;
const ll MOD = 1e9 + 7;
const double pi = 3.14159265;
ll t;
ll n;
int main() {
  cin.tie(0);
  cout.tie(0);
  cin.sync_with_stdio(false);
  cout.sync_with_stdio(false);
  cout.precision(15);
  cin >> t;
  for (ll(rock) = 0; (rock) < (t); ++(rock)) {
    cin >> n;
    n *= 4;
    double deg0 = (n - 2) * 180 / (double)n;
    double alfa = deg0 / 2;
    double sin_alfa = sin(alfa * pi / 180);
    double s = 1 / (2 * sin_alfa);
    double deg = 360 / (double)(n);
    double sin_a = sin(deg * pi / 180);
    double b = 90 - deg / 2;
    double sin_b = sin(b * pi / 180);
    double R = sin_b * s / sin_a;
    double h = R * R * sin_a / s;
    cout << 2 * h << endl;
  }
  return 0;
}
