
Learning Objective:
What is Factorial?
What is n x (n - 1)!
Concept:
The product of 'n' natural numbers is called factorial.
For example if we multiply first 5 natural numbers, we obtain 5 factorial and if we multiply first 10 natural numbers, we obtain 10 factorial.
Factorial is denoted as "!". So the product of n natural numbers is n! (read as n factorial).
For example 1 x 2 x 3 .....n = n!
For example (Reverse Order) n x (n-1) x (n-2) ..... x 3 x 2 x 1 = n!
For example 1 x 2 x 3 x 4 x 5 = 5!
For example (Reverse Order) 5 x 4 x 3 x 2 x 1 = 5!
For example 1 x 2 x 3 x 4 x 5 x 6 = 6!
For example (Reverse Order) 6 x 5 x 4 x 3 x 2 x 1 = 6!