for _ in range(int(input())):
    l, r = 1e-6, 12.22e74
    for _ in range(24):
        c = (l*r) ** 0.5
        print(f'? {c:.8f}')
        if input() == 'Yes':
            l = c
        else:
            r = c
    print(f'! {2*l*r / (l+r):.8f}')