def query(x):
        print('?', '{0:.10f}'.format(x),flush=True)
        s = input()
        if s == -1:
            exit()
        return True if s == 'Yes' else False

def solve():
    ng = 0
    ok = 1222 * pow(10, 72)
    while True:
        if abs(ng - ok) / abs(ok) <= pow(10, -5) or abs(ng - ok) <= pow(10, -5):
            print('!', '{0:.10f}'.format(ok),flush=True)
            break
        mid = ok * pow(10, -5)
        if query(mid):
            ok = mid
        else:
            continue
t = int(input())
for _ in range(t):
    solve()