What is the greatest value of x such that 4^x is a factor of 21! ? Pick one:
A) 5 B) 6 C) 3 D) 2 E) 4
Pretty simple, really.   If m = 6, then 4m = 24, which is 12x2, both of which are included in 21!   Since 6 is the largest number here, its the answer.   Answer is 6
<result>B</result>
What is the greatest value of x such that 4^x is a factor of 21! ?