use std::io::Read;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_to_string(&mut s).ok();
	let mut itr = s.trim().split_whitespace();
	itr.next();
	for i in itr {
		let r: f64 = i.parse().unwrap();
		println! ("{}", 3. * (3 as f64).sqrt() / 4. * r * r );
	}
}