T=int(input())
for t in range(T):
    l=1e-6
    r=12.22*1e74
    for _ in range(24):
        mid=(l*r)**.5
        print(f"? {mid:.12f}")
        S=input()
        assert S!="-1"
        if S=="Yes":
            l=mid
        elif S=="No":
            r=mid
        else:
            exit()
    ans=2*l*r/(l+r)
    print(f"! {ans:.12f}")