how many positive integers h less than 10000 are such that the product of their digits is 210 ?	Choose one
A) 24  B) 30  C) 48  D) 54  E) 72

Rationale: 210 is the answer when 2 , 3 , 5 and 7 are multiplied . 210 can also be arrive using 56 and 7 and 1 , 5 , 6 and 7 . so sum of arrangements of 2357 , 567 and 1567 . this translates to 4 ! + 3 ! + 4 ! , this equals to 24 + 6 + 24 = 54 , d is the answer .
Answer: D