#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
double fun(int n)
{
	if (n == 1)
		return 1;
	else
		return fun(n-1)+1/pow(2, n-2);
}
int main()
{
	int m;
	cin >> m;
	while (m--) {
		int H, n;
		cin >> H >> n;
		printf("%.2f\n", H*fun(n));
	}
	return 0;
}