N=int(input())
from decimal import Decimal
for _ in range(N):
  x,y=input().split()
  y=int(y)
  if x[-2]=='.':
    x=x+'00'
  elif x[-2]=='.':
    x=x+'0'
  x=int(x.replace('.',''))
  ans=0;c=1
  for i in range(1,y):
    d=Decimal(c*x)/Decimal(1000) 
    ans+=i*d 
    c-=d
    if c<0.0000001:
      break
  print(ans+y*c)