1.1.4.2 Permutation and Combination

In this video, you will get the idea of Permutation and Combination.

Permutations: Unique arrangements of items
1 of 2. Linear Permutation
Number of unique possible ways a set of items can be arranged in a line taken some or all at a time.

2 of 2. Circular Permutation
Clockwise and anti-clockwise direction produce DIFFERENT arrangements: (n-1)! permutations
Clockwise and anti-clockwise direction produce SAME arrangements: (n-1)!/2 permutations.

Combination: Grouping of items (Position has no effect in counting) taken some or all at a time