A baseball team has 13 players; how many possible batting orders can the coach make if there are 9 players in the batting lineup?

Answer 1

13 choose 9

13!/(9!*4!)

Answer 2

Batting "order" implies that the order they play is important, so

13 P 9
= 13*12*11*10*9*8*7*6*5
= ....