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

using namespace std;
#define MOD 998244353
int main() {
    int T;
    cin >> T;
    for (int i=0; i<T; i++) {
        double p;
        int K;
        cin >> p >> K;

        double ret=0.0;
        if (p == 1.0) { ret=1.0; }
        else {
            double pdash = 1.0;
            for (int j=1; j<K; j++) {
                ret += j*pdash*p;
                pdash = pdash * (1.0-p);
            }
            ret += K*pdash;
        }
        printf("%.11f\n", ret);
    }
    return 0;
}