new_contents: num = int(input("Enter a number: "))
  factorial = 1
  
  if num < 0:
     print("Sorry, factorial does not exist for negative numbers")
  elif num == 0:
     print("The factorial of 0 is 1")
  else:
     for i in range(1,num + 1):
         factorial = factorial*i
     print("The factorial of",num,"is",factorial)
  
subject: add factorial.py