Which of the following is an integer?
I. 13! / 6!
II. 13! / 8!
III. 13! / 7!5!
Choose the correct choice from the following.
A) I only B) II only C) III only D) I and II only E) I, II and III
13!/6! = 13*12*11*10*9*8*7 which is an integer.   13!/8! = 13*12*11*10*9 which is an integer.   13!/7!5! = 13*12*11*10*9*8 / 5*4*3*2 = 13*12*11*3*2 which is an integer.   The answer is I, II and III.
<result>E</result>
Which of the following is an integer?
I. 13! / 6!
II. 13! / 8!
III. 13! / 7!5!