abcd = efgh * i

a * 10^3 + b * 10^2 + c * 10^1 + d * 10^0 =
      (e * 10^3 + f * 10^2 + g * 10^1 + h * 10^0) * i

=> (e*i-a)*10^3 + (f*i-b)*10^2 + (g*i-c)*10^1 + (h*i-d)*10^0 = 0

for the above to have a chance to be zero:
1)
  ((h*i-d) * 10^0) % 10^1 = 0  (e.g. must end in 0)
2)
  The cumulative sum of the above at position J,
  (i.e. from right to left, J=0 for the term (h*i-d) * 10^0 )
  must also end in zeros as follows:
   cum-sum at pos J=1 must end in 00
   cum-sum at pos J=2 must end in 000
    etc.
3)
  The cumulative sum of the above at position J,
  from right to left must also not be less than:
    cum-sum at pos J+1 >= 100
    cum-sum at pos J+2 >= 1000
      etc.