#include<bits/stdc++.h>
#define poly vector<int>
#define IOS ios::sync_with_stdio(false)
#define ll long long
#define mp make_pair
#define mt make_tuple
#define pa pair < int,int >
#define fi first
#define se second
#define inf 1e18
#define mod 998244353
#define sz(x) (int)((x).size())
#define int ll
//#define N
using namespace std;

inline double quickPower(double x,ll y)
{
	double res=1;
	while (y)
	{
		if (y&1) res=res*x;
		x=x*x;
		y>>=1;
	}
	return res;
}
void BellaKira()
{
	double p;
	int n;
	cin>>p>>n;
	double ans=0;
	for (int i=1;i<=n;i++)
	{
		ans+=p*quickPower(1.0-p,i-1)*i;
	}
	ans+=quickPower(1.0-p,n)*n;
	cout<<fixed<<setprecision(10)<<ans<<'\n';
}
signed main()
{
	IOS;
	cin.tie(0);
	int T=1;
	cin>>T;
	while (T--)
	{
		BellaKira();
	}
}