#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000000000000000

bool query(long double x){
	cout<<"? "<<fixed<<setprecision(100)<<x<<endl;
	string ans;
	cin>>ans;
	if(ans[0]=='Y')return true;
	else return false;
}
void answer(long double x){
	cout<<"! "<<fixed<<setprecision(100)<<x<<endl;
}
void solve(){
	long double ok = 0.0,ng = 1.0;
	bool f = query(1.0);
	if(!f){
		long double ok = 0.0,ng = 1.0;
		rep(_,22){
			long double m = (ok+ng)/2.0;
			if(query(m))ok = m;
			else ng = m;			
		}
		answer(ok);
	}
	else{
		long double ok = 1.0,ng = 12.22 * powl(10.0,74);
		rep(_,22){
			long double m = sqrtl(ok)*sqrtl(ng);//sqrt(ok*ng);
			if(query(m))ok = m;
			else ng = m;			
		}
		answer(ok);
	}
}
int main(){
	
	int _t;
	cin>>_t;
	rep(_,_t){
		solve();
	}
	
	return 0;
}