"""

"""

import sys
from sys import stdin

TT = int(stdin.readline())

for qloop in range(TT):

    L = 10**-6
    R = 12.22*(10**74)

    for loop in range(24):

        M = (L*R)**0.5
        print ("?","%f" % M,flush=True)

        S = stdin.readline()[:-1]
        if S[0] == "Y":
            L = M
        elif S[0] == "N":
            R = M
        else:
            sys.exit(1)

    print ("!", "%f" % ((L*R)**0.5) , flush=True)