#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(LL i = a;i<b; i++)
#define rrep(i,a,b) for(LL i = a;i>=b; i--)
#define INF ((1LL<<62)-(1LL<<31))
#define ooki 9,223,372,036,854,775,807
#define tii -9,223,372,036,854,775,808
typedef long long LL;
int main(){
 int t;
  cin >> t;
  rep(i,0,t){
    double r;
    cin >> r;
    double an =3*sqrt(3)*r*r/4;
cout<<fixed<<setprecision(30)<<an<<endl;
  }
}