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
def solve():
    upper = 12.22 * pow(10, 74)
    lower = 0
    for i in range(24):
        now = random.randint(lower, upper)
        if query(now):
            upper = now
        else:
            lower = now
    print('!', '{0:.10f}'.format(upper),flush=True)


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