some factorials

x = 4

4! =24

(4 - 3)! =1

24 - 1 = 23

23 / 23 =1

x! - (x-3)! = 23

x!    and     (x-3)!   have a difference of 23

x(x-1)(x-2)(x-3)(x-4)....     -   (x-3)(x-4).....

x = 4      just by looking at it......not sure how to do it mathematically... 

Good work!