import math from decimal import * getcontext().prec = 200 def query(y): print('? {:.20f}'.format(y), flush=True) s = input() assert(s != "-1") return s == "Yes" # https://codeforces.com/blog/entry/49189 # https://twitter.com/maspy_stars/status/1369696139683844097 def solve(): Q = 24 if query(167.7717663): lb = Decimal(167.7717663) ub = Decimal(1222) * (Decimal(10) ** 72) for _ in range(1, Q): mid = (lb * ub).sqrt() if query(mid): lb = mid else: ub = mid print('! {:.20f}'.format((lb * ub * 2) / (lb + ub)), flush=True) else: lb = Decimal(0) ub = Decimal(167.7717663) for _ in range(1, Q): mid = (lb + ub) / 2 if query(mid): lb = mid else: ub = mid print('! {:.20f}'.format((lb + ub) / 2), flush=True) t = int(input()) for _ in range(t): solve()