#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
//okita

int main(){
   ll T;cin>>T;
   rep(i,T){
       double A;cin>>A;
       cout<<1.732050*3*A*A/4<<endl;
   }
}