#include <iostream>
#include <iomanip>
using namespace std;

int main(){
    int t; cin >> t;
    while(t--){
        double p; cin >> p;
        int k; cin >> k;

        double ans = 0.0;
        double c = 1.0;
        for(int i = 1; i < k; i++){
            ans += c*p*i;
            c *= 1.0-p;
        }
        ans += c*k;

        cout << fixed << setprecision(10) << ans << '\n';
    }
    return 0;
}