/* -*- coding: utf-8 -*-
 *
 * 2461.cc:  No.2461 一点張り - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    double p;
    int k;
    scanf("%lf%d", &p, &k);

    double q = 1.0, e = 0.0;
    for (int i = 1; i < k; i++) {
      e += q * p * i;
      q *= 1.0 - p;
    }
    e += q * k;

    printf("%.11lf\n", e);
  }
  return 0;
}