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

void solve(){
	double p; cin >> p;
	int k; cin >> k;
	double now = 1;
	double ans = 0;
	for(int i=1; i<k; i++){
		ans += now * p * i;
		now *= 1 - p;
	}
	ans += now * k;
	cout << fixed << setprecision(15);
	cout << ans << '\n';
}

int main(){
	int t; cin >> t;
	while(t--) solve();
}