def query(x):
        print('?', '{0:.10f}'.format(x),flush=True)
        s = input()
        if s == '-1':
            raise Exception
        return True if s == 'Yes' else False
import random
from math import log10
def solve():
    upper = log10(12.24) + 74
    lower = -10
    for i in range(24):
        now = random.uniform(lower, upper)
        if query(pow(10,now)):
            upper = now
        else:
            lower = now
    print('!', '{0:.10f}'.format(pow(10, upper)),flush=True)


t = int(input())
for _ in range(t):
    solve()