#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--;) {
        double p;
        int k;
        cin >> p >> k;
        if (p == 0) {
            cout << k << endl;
        } else if (p == 1) {
            cout << 1 << endl;
        } else {
            double pk = pow(1 - p, k);
            double ans = (k * p * pk - p * pk + pk + p - 1) / (p - 1) / p +
                         k * pk / (1 - p);
            cout << setprecision(16) << fixed << ans << endl;
        }
    }
}