#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main(){
    int t;
    cin >> t;
    while(t--){
        double r;
        cin >> r;
        cout << fixed << setprecision(10) << (r * r * sqrt(3) / 4 * 3) << "\n";
    }

    return 0;
}