# IndentationError: unindent does not match any outer indentation level

Created by Kevin TigheLinked to 64.4m issues across 157 teams

## tl;dr

Here's how to write a function in Python that calculates the factorial of a given number.

First, start by importing the sys module:

``````import sys
``````

Next, define the function Factorial, which will take one argument, n, and return the factorial of that number:

``````def Factorial(n): # return factorial
``````

Inside the function, create a variable called result and set it to 1. This will be used to store the result of the calculation:

``````result = 1
``````

Now, create a `for` loop that will iterate from 1 to n. For each iteration, multiply the result by the current value of i and store the result in the result variable:

``````for i in range (1,n):
result = result * i
``````

Finally, print the result and return it:

``````print "factorial is ",result
return result
``````

Now, you can call the function with any number to get the factorial of that number:

``````print Factorial(10)
``````