#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
	int t;
	cin >> t;
	while(t--){
		lb p;
		int k;
		cin >> p >> k;
		lb ans = 0;
		lb now = 1;
		for(int i=1;i<=k-1;i++){
			ans += i*now*p;
			now *= (1-p);
		}
		ans += now*k;
		cout << fixed << setprecision(16)<< ans << endl;
	}
	return 0;
}