N=int(input())
for j in range(N):
  x,y=input().split()
  y=int(y)
  if x[-2]=='.':
    x=x+'00'
  elif x[-3]=='.':
    x=x+'0'
  x=int(x.replace('.',''))
  ans=0;c=1
  for i in range(1,y):
    d=c*x*pow(10,-3) 
    ans+=i*d 
    c-=d
  e=ans+y*c 
  print(e)