#include <bits/stdc++.h>
#include <atcoder/mincostflow>
#include <atcoder/segtree>
using namespace std;
using namespace atcoder;
#define int long long
using vec_int = vector<int>;
using P = pair<int,int>;
using T = tuple<int,int,int>;
using ll = long long;
#define rep(i, n) for(int i = 0; i < (int)(n); i++)

int charToInt(char c){
    char zero_num = '0';
    return (int)c - (int)zero_num;
}

void cout_line(vector<int> &a){
    for(int i=0;i<a.size();i++){
        if(i<a.size()-1){
            cout<<a.at(i)<<" ";
        }else{
            cout<<a.at(i)<<endl;
        }
    }
}

signed main(){
    int t; cin>>t;
    rep(tt, t){
        long double r; cin>>r;
        long double ans = sqrt(3)*3./4.*r*r;
        cout<<fixed<<setprecision(10)<<ans<<endl;

    }

    return 0;
}