### What is Factorial of a number?

Product of all consecutive Integer numbers up to n is called Factorial of a Number and is denoted by n! For Example, the value of 5! is 120.

Mathematically it is written as,

n! = 1 * 2 * 3 * 4 * ... * (n-1) * n

For example, the factorial of 5 is,

5! = 1 * 2 * 3 * 4 * 5 = 120

### Algorithm for Finding Factorial of a Number

Step 1: Start
Step 2: Declare Variable n, fact, i
Step 3: Read number from User
Step 4: Initialize Variable fact=1 and i=1
Step 5: Repeat Until i<=number
5.1 fact=fact*i
5.2 i=i+1
Step 6: Print fact
Step 7: Stop
### Pseudocode for Finding Factorial of Number

Read number
Fact = 1
i = 1
WHILE i<=number
Fact=Fact*i
i=i+1
ENDWHILE
WRITE Fact
#### Explanation

We first take input from user and store that value in variable named “n”. Then we initialize a variable “Fact” with value 1 (i.e Fact=1) and variable i with value 1(i.e i=1). Repeat next two steps until i is less than n.

- Multiply Fact with current value of i
- Increment i with 1

At last, print the value of Fact.

Let’s take an example,

Let the input be 5.

The equation that gets created by our algorithm is 5x4x3x2x1.

So, The Factorial of 5 is 120(5x4x3x2x1).