use std::io::Read;
fn main() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let r: Vec<f64> = s.split_whitespace().flat_map(str::parse).collect();
    r[1..].iter().for_each(|r| {
        println!("{}", 27f64.sqrt() * r * r / 4.);
    });
}