#include <iostream>
#include <stdio.h>
#include <vector>

using namespace std;

using i64 = long long;

#define yn(pope) (pope ? "Yes" : "No")

#define rep(i, n, m) for (int i = (n); i < (m); i++)
#define rrep(i, n, m) for (int i = (n); i > m; i--)

#define IINF (1 << 30)
#define INF (1ll << 60)

#define all(v) v.begin(), v.end()

int main() {
  int T; cin >> T;

  while (T--) {
    double p;
    int K; cin >> p >> K;

    double ans = 0;
    double rem = 1;

    rep(i, 1, K) {
      ans += i * rem * p;
      rem *= (1 - p);
    }

    ans += K * rem;

    cout << fixed << ans << endl;
  }

  return 0;
}