for _ in range(int(input())):
    r = 12.22 * 10 ** 74
    l = 10 ** -6
    for _ in range(24):
        mid = (l * r) ** 0.5
        print(f"? {mid:.12f}", flush=True)
        res = input()
        if res == "Yes":
            r = mid
        elif res == "No":
            l = mid
        else:
            assert False
            exit()

    ans = (l * r) ** 0.5
    print(f"! {ans:.12f}", flush=True)