#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <tuple>
#include <random>
#include <stdio.h>
#include <bitset>
#include <cassert>

using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef tuple<int, int, vector<int>> T;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

double get_elapsed_time(struct timeval *begin, struct timeval *end) {
    return (end->tv_sec - begin->tv_sec) * 1000
	+ (end->tv_usec - begin->tv_usec) / 1000.0;
}

unsigned long xor128(void) {
    static unsigned long x=123456789,y=362436069,z=521288629,w=88675123;
    unsigned long t;
    t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) );
}

// [0, k)
int rand(int k) {
    return xor128() % k;
}

random_device seed_gen;
ranlux24 engine(seed_gen());

double error(const double x, const double y) {
    return min(abs(x - y) / x, abs(x - y));
}

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();
}

void input() {

}

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

    int t;
    cin >> t;
    for (int i = 0; i < t; i++) {
        //input();
        solve();
    }
}