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

int main() {
	int T;
	cin >> T;
	for( int i = 0; i < T; i++ ) {
		double p;
		int K;
		cin >> p >> K;
		double ans = 0, pp, rp;
		if( p == 1 ) ans = 1;
		else {
			for( int k = 0; k < K; k++ ) {
				if( k == 0 ) ans += (k + 1) * p;
				else if( k == 1 ) {
					rp = 1 - p;
					pp = rp;
					if( k == K - 1 ) ans += (k + 1) * rp;
					else ans += (k + 1) * rp * p;
				}
				else {
					rp *= pp;
					if( k == K - 1) ans += (k + 1) * rp;
					else ans += (k + 1) * rp * p;
				}
			}
		}
		cout << fixed << setprecision(12) << ans << endl;
	}
}