#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for(int i=(a); i<(n); i++)
#define rrep(i,a,n) for(int i=(a); i>=(n); i--)
#define all(n) begin(n),end(n)
#define rall(n) rbegin(n),rend(n)
//#define yn(bool) if(bool){cout<<Yes<<endl;}else{cout<<No<<endl;}
#define fore(i,a) for(auto &i:a)
using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
ll myceil(ll a,ll b){return (a+(b-1))/b;}
ll myfloor(ll a,ll b){return a/b;}
template <typename T> inline bool chmin(T& a, const T& b) {bool compare = a > b; if (a > b) a = b; return compare;}
template <typename T> inline bool chmax(T& a, const T& b) {bool compare = a < b; if (a < b) a = b; return compare;}
void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }

void _main() {
    int t;
    cin>>t;
    rep(i,0,t) {
        double r;
        cin>>r;
        printf("%.6f\n",3*sqrt(3)*r*r/4);
    }
}