Factorial notation  Permutations and Combinations
Factorial notation
Basic concepts:
 Solving rational equations
Lessons

2.
factorial notation: n! = n (n1) (n2) (n3) (n4) . . . . . (5) (4) (3) (2) (1)
by definition : 0! = 1 
a)
DOG

b)
MATH

c)
COMPUTER
