#include <stdio.h>

double solve(double p, int K)
{
	int i;
	double ans = 0.0, tmp;
	for (i = 1, tmp = 1.0; i < K; i++, tmp *= 1.0 - p) ans += i * tmp * p;
	return ans + K * tmp;
}

int main()
{
	int T, K;
	double p;
	scanf("%d", &T);
	while (T--) {
		scanf("%lf %d", &p, &K);
		printf("%.6f\n", solve(p, K));
	}
	fflush(stdout);
	return 0;
}