import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import log,gcd
from fractions import Fraction

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

def query(y):
    if y < 100:
        print("? {:.100f}".format(y))
    else:
        print("? {:.100g}".format(y))
    sys.stdout.flush()
    #return True
    res = input()
    assert res!="-1"
    return res=="Yes"

def answer(x):
    if x < 100:
        print("! {:.100f}".format(x))
    else:
        print("! {:.100g}".format(x))
    sys.stdout.flush()

for _ in range(int(input())):
    ok = 10**(-5.5)
    ng = 10**74 * 12.22
    for i in range(24):
        mid = (ok*ng)**.5
        if query(mid):
            ok = mid
        else:
            ng = mid
    mid = (ok*ng)**.5
    answer(mid)