# Program to find factorial of a number in python

Factorial(!) of a number (N) is the multiplication of all numbers from 1 to N. Formula is as defined below.

``````N! = 1 * 2 * 3 * 4 ... N
# for example
4! = 1 * 2 * 3 * 4 = 24``````

In this article, we are going to write a python program (in all different ways) to find the factorial of the given number.

#### Factorial of a number in python using loops

``````# factorialnum.py
# The function returns the factorial of given number.
def factorial(num):
if num < 1:
return -1
fact = 1
# multiply all numbers from 2 to N.
for i in range(2, num+1):
fact = i * fact
return fact

# prints the factorial of 4.
print(factorial(4))``````

In the above program, we are using for loop to multiply all numbers from 1 to N. The output of the above code is as shown below.

``````# Output
\$python factorialnum.py
24``````

We can even find the factorial numbers in python using a recursion function.

``````# Recursion function for factorial.
F(N) = N * F(N-1)``````

#### Let’s write the python code to find factorial using recursion.

``````# factorialrecur.py
# The function returns factorial using recursion.
def factorialRecur(num):
if(num < 2):
return 1
return num * factorialRecur(num-1)

# prints the factorial of 4.
print(factorialRecur(4))``````

The output of the above code is as follows.

``````# Output
\$ python factorialrecur.py
24``````

These are the two methods to identify the factorial of any given number using python programming. Hope this article helps you to understand the factorial in python. Happy learning!!.