If n is a positive integer and the product of all integers from 1 to n, inclusive, is a multiple of 840, what is the least possible value of n?
Pick one:
A) 5 B) 6 C) 7 D) 8 E) 9

Rationale: 840 = 2 * 2 * 2 * 3 * 5 * 7 , so n must be at least 7 . the answer is c .
Answer: C