use std::io::Read;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_to_string(&mut s).ok();
	for l in s.lines().skip(1) {
		let v: Vec<f64> = l.split(' ').flat_map(str::parse).collect();
		let mut a = 0.;
		for i in 1..v[1] as i32 {
			a += v[0] * (1. - v[0]).powi(i - 1) * i as f64;
		}
		println!("{}", a + (1. - v[0]).powi(v[1] as i32 - 1) * v[1])
	}
}