#line 1 "main.cpp"
#include <bits/stdc++.h>

using namespace std;

void solve() {
  double lb = 1e-6, ub = 1.222e75;
  int i;
  string s;
  for (i = 0; i < 24; i++) {
    const double m = sqrt(lb * ub);
    cout << "? " << m << endl;
    cout.flush();
    cin >> s;
    if (s == "Yes") {
      lb = m;
    } else {
      ub = m;
    }
  }

  const double y = (lb + ub) / 2;
  cout << "! " << y << endl;
  cout.flush();
}

signed main(int argc, char *argv[]) {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << setprecision(15);

  int T;
  cin >> T;
  for (int i = 0; i < T; ++i) { solve(); }

  return 0;
}