#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (int i = 0; i < n; ++i)

void solve()
{
    double r;
    cin >> r;
    cout << 3 * sqrt(3) * pow(r, 2) / 4 << endl;
}

int main(void)
{
    int t;
    cin >> t;
    rep(i, t) solve();
}