#include <bits/stdc++.h>
#include <iterator>
using namespace std;
#define rep(i, n) for(int i=0; i<n; i++)
#define debug 1
using ll = long long;
using ld = long double;
const int mod = 998244353;
const double pi = atan2(0, -1);
#include <time.h>
#include <chrono>

int main() {
	int T;
	cin >> T;
	rep(test, T) {
		double p;
		int K;
		cin >> p >> K;
		vector<double> v(K);
		v[0] = 1;
		rep(i, K - 1) {
			v[i + 1] = v[i] * (1-p);
		}
		double ans = 0;
		for (int i = 1; i < K; i++) {
			ans += v[i - 1] * p * i;
		}
		ans += v[K - 1] * K;
		cout << fixed << setprecision(10);
		cout << ans << endl;
	}
}