(((13!)^16)-((13!)^8))/(((13!)^8)+((13!)^4))=a
then what is the units digit for a/((13!)^4)=	Choose the correct option.
A) 7	B) 8	C) 9	D) 6	E) 5

Rationale: ( ( ( 13 ! ) ^ 16 ) - ( ( 13 ! ) ^ 8 ) ) / ( ( ( 13 ! ) ^ 8 ) + ( ( 13 ! ) ^ 4 ) ) = a solving it , we get a / ( ( 13 ! ) ^ 4 ) = ( ( 13 ! ) ^ 4 - 1 ) last digit of ( 13 ! ) ^ 4 will be 0 . so last digit of ( ( 13 ! ) ^ 4 - 1 ) will be 9 . answer : c
Answer: C