Răspuns :
!= nr factorial
9! =1.2.3......8.9
8! = 1.2.3......8
9!-8! = 1.2.3.......8.9 - 1.2.3......8 = 1.2.3.......8 ( 9-1)= 1.2.3...8 x8
9! =1.2.3......8.9
8! = 1.2.3......8
9!-8! = 1.2.3.......8.9 - 1.2.3......8 = 1.2.3.......8 ( 9-1)= 1.2.3...8 x8