Q=int(input())
for _ in range(Q):
  result=0
  p,K=map(float,input().split())
  K=round(K)
  ans=1
  w=0
  for x in range(1,K):
    result+=x*(ans*p)
    w+=ans*p
    ans*=1-p
  result+=K*(1-w)
  print(result)