package main

import . "fmt"

func main() {
	var t int
	Scan(&t)
	for ;t>0;t-- {
		p,k:=0.0,0
		Scan(&p,&k)
		if k==1 {
			Println(1)
			continue
		}
		
			if p==0 {
				Println(k)
				continue
			} else if p==1 {
				Println(1)
				continue
			}
			
		
		r:=1-p
		g:=r
		s:=p
		for i:=2;i<k;i++ {
			z:=float64(i)*g*p
			s+=z
			g*=r
		}
		s+=float64(k)*g
		Printf("%.10f\n",s)
	}
}