Rewrite each of the following using factorial notation.

a. n(n – 1) (n – 2) (n – 3)

b. n(n – 1) (n – 2) (n – 3) (n – 4) (n – 5)

c. n(n – 1)(n – 2)/5 × 4 × 3 × 2 × 1

d. n(n- 1) (n – 2) (n – 3) (n – 4)/ 3 × 2 × 1