fn read() -> String {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    String::from(s.trim())
}

fn run() {
    let mut l = 10f64.powi(-5);
    let mut r = 12.22f64 * 10f64.powi(74);
    for _ in 0..24 {
        let m = (l * r).sqrt();
        println!("? {}", m);
        let ans = read();
        match ans.as_str() {
            "Yes" => l = m,
            "No" => r = m,
            _ => unreachable!(),
        }
    }
    let m = (l * r).sqrt();
    let abs = (m - l).abs().max((r - m).abs()) <= 1e-5;
    let re = r - m <= 1e-5 * r && m - l <= 1e-5 * l;
    assert!(abs || re);
    println!("! {}", (l * r).sqrt());
}

fn main() {
    let t = read().parse::<u32>().unwrap();
    for _ in 0..t {
        run();
    }
}