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

const double EPS = 1e-10;

double f(double T, double mu, double L) {
    double V = 36 * (sqrt(T * T + L / (5 * mu)) - T) * mu;
    if (abs(V) < EPS) V = 0;
    return V;
}

int main() {
    int N;
    cin >> N;
    for (int i = 0; i < N; ++i) {
        double T, mu, L;
        cin >> T >> mu >> L;
        double V = f(T, mu, L);
        cout << fixed << setprecision(2) << (int)(V * 100) / 100.0 << endl;
    }
}