#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    int t;
    cin >> t;

    while (t--) {
        int r;
        cin >> r;

        cout << fixed << setprecision(15) << (double)r * r * sqrt(3) * 0.25 * 3 << '\n';
    }

    return 0;
}