#include <bits/extc++.h>
#include <boost/multiprecision/cpp_int.hpp>

int main() {
    using namespace std;
    using bigint = boost::multiprecision::cpp_int;
    unsigned T;
    cin >> T;
    for ([[maybe_unused]] const auto _ : views::repeat(monostate{}, T)) [] {
        unsigned N;
        double _x;
        cin >> N >> _x;
        int X = round(_x * 100000), Y = 100000;
        int g{gcd(X, Y)};
        X /= g;
        Y /= g;
        bigint real = 1, imag = 0;
        for (unsigned i{8}; i--; ) {
            tie(real, imag) = pair<bigint, bigint>{real * real - imag * imag, real * imag * 2};
            if (N + 1 >> i & 1)
                tie(real, imag) = pair<bigint, bigint>{-real * X - imag * Y, real * Y - imag * X};
        }
        long abs_sq = static_cast<long>(X) * X + static_cast<long>(Y) * Y;
        int abs_round = round(sqrt(abs_sq));
        bigint ans;
        if (abs_sq == static_cast<long>(abs_round) * abs_round) {
            bigint abs_div = abs_round;
            ans = max(imag, -imag) * g;
            for (unsigned i{}; i < 8; ++i) {
                if (N >> i & 1)
                    ans /= abs_div;
                abs_div *= abs_div;
            }
        } else {
            bigint abs_div = abs_sq;
            bigint mag_sq = imag * imag * g * g;
            for (unsigned i{}; i < 8; ++i) {
                if (N >> i & 1)
                    mag_sq /= abs_div;
                abs_div *= abs_div;
            }
            ans = static_cast<bigint>(sqrt(static_cast<double>(mag_sq)) + 1);
            if (mag_sq != 0) {
                do {
                    ans = (ans + mag_sq / ans) / 2;
                } while (mag_sq / ans / ans == 0);
            }
        }
        cout << (imag < 0 ? "-" : "") << ans / 100000 << "." << setw(5) << setfill('0') << ans % 100000 << endl;
    }();
    abort();
    return 0;
}