#include <stdio.h>

int main () {
  int t = 0;
  double p = 0.0;
  int k = 0;
  
  int res = 0;
  
  res = scanf("%d", &t);
  while (t > 0) {
    double ans = 0.0;
    double acc = 1.0;
    res = scanf("%lf", &p);
    res = scanf("%d", &k);
    for (int i = 0; i < k-1; i++) {
      ans += acc*p*((double)(i+1));
      acc *= 1.0-p;
    }
    ans += acc*((double)k);
    printf("%.16lf\n", ans);
    t--;
  }
  
  return 0;
}