#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
//using mint = modint998244353;
//std::chrono::time_point<std::chrono::steady_clock> start;
template <typename T> bool chmax(T &u, const T z) { if (u < z) {u = z; return true;} else return false; }
template <typename T> bool chmin(T &u, const T z) { if (u > z) {u = z; return true;} else return false; }
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
typedef pair<ll, int> P;
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll lcm(ll a, ll b){return a * b / gcd(a, b);}
template<class T, class U>
//contain(string s,string v) sにvが含まれるかを判定
bool contain(const std::basic_string<T>& s, const U& v) {
   return s.find(v) != std::basic_string<T>::npos;
}
const int mod=1000000007;
struct combination {
  vector<mint> fact, ifact;
  combination(int n):fact(n+1),ifact(n+1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n]*ifact[k]*ifact[n-k];
  }
};

int main(){
  int t;
  cin>>t;
  while(t--){
    double r;
    cin>>r;
    double ans=(double)3/4*r*sqrt(3)*r;
    cout<<fixed<<setprecision(12)<<ans<<endl;
  }
  return 0;
}