Permutation & Combination

What is Permutation?

The number of different ways that a certain number of objects can be arranged in order from a large name of objects. Below are the hints when you encounter a problem :

(1) Order matters, An order list.
(2) Arrangement.

What is Combination?

The number of different ways that a certain number of objects as a group can be selected from a layer number of objects. Below are the keys when you encounter a problem :

(1) Group
(2) Sample
(3) Choice
(4) Election
(5) Collection

Ways:
1! = 1 way
2! = 2 ways
3! = 6 ways
4! = 24 ways
5! = 120 ways

Symbols:
N! = Permutation
! = Factorial
n = number selected

The Formula?

Example & Questions :

Suppose there are 12 people and only 8 people are invited to a party. In how many ways can the party be selected?

Solution :

Answer of  Example 1 ( Combination )

Example 2 :

Answer of example 2 (Permutation)