#include <bits/stdc++.h>

using namespace std;

void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int main() {
    fast_io();
    int t;
    cin >> t;
    for (; t--;) {
        int r;
        cin >> r;
        cout << setprecision(16) << fixed << r * r * 3 * sqrt(3) / 4 << "\n";
    }
}