• A factorial is a mathematical operation you write like this n!. It represents the multiplication of all numbers between 1 and n. ```

    Returns the value of the factorial of num if it is defined, otherwise, returns None

    def factorial(num): # This helps with floats such as 1.2 and a string of “spam spam spam spam” if type(num) is not int: return None # Takes into account -2, which is valid. if num < 0: return 1 if num == 0: return 1 # Calculates the factorial. # i = the index of how many iterations we have done in the loop. i = 0 # f = factorial that we will return. f = 1 while i < num: i = i + 1 # Updates itself. f = f * 1

       return f

def factorial(num): if type(num) is not int: return None if num < 0: return None if num == 0: return 1

	 return num * factorial(num - 1)

return 120

factorial(5)

return 720

factorial(6)

return 1

factorial(0)

return None

factorial(-2)

return None

factorial(1.2)

return None

factorial(‘spam spam spam spam spam spam’) ```

  • Recursion = The function calling itself.

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