### Factorial of a number:

The product of all positive integers less than or equal to n is the factorial of a non-negative integer n, denoted by n! in mathematics:

**n! = n * (n – 1) *(n – 2) * . . . . . . . . . . 3 * 2 * 1.**

4 != 4 * 3 * 2 * 1

**Examples:**

**Input:**

number = 7

**Output:**

Factorial of 7 = 5040

Given a number , the task is to find the factorial of the given number

## Finding Factorial of a Number

There are several ways to find factorial of a number in python some of them are:

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### Method #1:Using for loop(Without Recursion)

**Approach:**

- Create a variable say res and assign it to 1.
- Using for loop and range, Run a loop from 1 to n.
- Multiply the res with the loop iterator value.

**Below is the implementation:**

# given number num = 7 # initializing a variable res with 1 res = 1 # Traverse from 1 to n for i in range(1, num+1): res = res*i # print the factorial print("Factorial of", num, "=", res)

**Output:**

Factorial of 7 = 5040

### Method #2: Using recursion

To find the factorial of a given number, we will use recursion. We defined the factorial(num) function, which returns 1 if the entered value is 1 and 0 otherwise, until we get the factorial of a given number.

**Below is the implementation:**

# function which returns the factorial of given number def facto(num): if(num == 1 or num == 0): return 1 else: return num*facto(num-1) # given number num = 7 # passing the given num to facto function which returns the factorial of the number res = facto(num) # print the factorial print("Factorial of", num, "=", res)

**Output:**

Factorial of 7 = 5040

### Method #3 : Using Built in Python functions

Python has a built-in function

`factorial (number)`

which returns the factorial of given number.

**Note:** factorial function is available in math module

**Below is the implementation:**

# import math module import math # given number num = 7 # finding factorial using Built in python function res = math.factorial(num) # print the factorial print("Factorial of", num, "=", res)

**Output:**

Factorial of 7 = 5040

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- python program to find the factors of a number
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**Related Programs**:

- python program to find the factors of a number
- python program to find all numbers in a range which are perfect squares and sum of all digits in the number is less than 10
- python program to find the power of a number using recursion
- python program to compute the power of a number
- python program to count the number of digits present in a number
- python program to find whether a number is a power of two
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