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

vector<ll> dx = { 0, 0, -1, 1};
vector<ll> dy = {-1, 1,  0, 0};

#define MOD 1000000007
int main() {
    int t;
    cin >> t;

    for (int i=0; i<t; i++) {
        int r;
        cin >> r;
        double area = (double)r*1.5*sqrt(3)/2;
        printf("%f\n", area);
    }
    return 0;
}