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

int main() {
    int T;
    cin>>T;
    while(T--){
        double P;
        int K;
        cin>>P>>K;
        double an=0;
        double p=1.0;
        for(int i=1;i<=K;i++){
            an+=p*P*double(i);
            p*=(1-P);
        }
        an+=p*double(K);
        cout<<fixed<<setprecision(15)<<an<<endl;
    }
}