#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <map>
#include <cmath>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i=0;i < (int)(n);i++)

int main(){
    int t;
    cin >> t;
    while(t--){
        double r;
        cin >> r;
        cout << 3.0*r*r*sqrt(3)/4.0 << endl;
    }
    return 0;
}