แฟคทอเรียล

380

56

810

20

0! = 1!

8! = 8 x 7 x 6!

$$\frac{9!}{8!}=9$$

$$\frac{0!2!}{2!}\ =\ 0$$

$$\frac{1}{2}$$

$$\frac{2}{3}$$

81

$$\frac{1}{14}$$

380

56

810

20

380

56

810

20

380

56

810

20

(n+1)

(n+2)

(n+2)(n+1)

(n+2)(n+1)n

$$\frac{10!}{7!}$$

$$\frac{9!}{2!}$$

$$\frac{43!}{39!}$$

$$\frac{50!}{47!}$$

$$\frac{10!}{7!}$$

$$\frac{9!}{2!}$$

$$\frac{43!}{39!}$$

$$\frac{50!}{47!}$$

$$\frac{\left(n+2\right)!}{\left(n-1\right)!}$$

$$\frac{\left(n+2\right)!}{\left(n-2\right)!}$$

$$\frac{\left(n+3\right)!}{\left(n-2\right)!}$$

$$\frac{n!}{\left(n-2\right)!}$$