TI-84 Commands: Factorials, Permutations, Combinations

How many ways can things be arranged or grouped or selected? This is a question for factorials, permutations, and combinations.
Factorials (n!) are the product of all whole numbers less than or equal to n.
If order matters, permutation (nPr) is the function to use: (n!)/(n-r)!
If order doesn’t matter, combination (nCr) is the function to use (n!)/((n-r)!(r!)).
The video uses TI-84 emulator to demonstrate operations on the calculator that makes the arithmetic faster and less susceptible to error.