#include <iostream>
#include<utility>
#include <vector>
#include <map>
#include<string>
#include<queue>
#include<math.h>
#define pb push_back
#define all(x) begin(x),end(x)
#define ll long long
#define P pair<int,int>
#define lP pait<ll,ll>
using namespace std;
int main() {
    int t=0;
    cin>>t;
    for(int i=0;i<t;i++){
        double a;
        cin>>a;
        printf("%.15lf\n",pow(a,2)*3/4*sqrt(3));
    }
    return 0;
}