#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define chmin(x,y) x = min((x),(y))
#define chmax(x,y) x = max((x),(y))
#define popcount(x) __builtin_popcount(x)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
const int INF = 1e9;
const long long LINF = 1e17;
const int MOD = 1000000007;
//const int MOD = 998244353;
const double PI = 3.14159265358979323846;

int main(){
    double three = sqrt(3);

    int t;
    cin >> t;
    while(t--){
        int r;
        cin >> r;
        cout << setprecision(20) <<  3*three*r*r/4 << endl;
    }
    return 0;
}