How do I ask user to input numbers to then store in text file?

Question

I need to have the user input a certain amount of numbers (5) and have them stored in a text file. I also need to find the average of those numbers. Would I use the sum function for that and then divide by 5?

This is for python and I use the IDLE 3.4 version on OS X.

lst = list() #creates a list to later store nubers in

def addtolist():  #creates a function for adding numbers to the list
  def listcount():  #
        try:
              lst.append(int(input("Enter a number:")))
        except ValueError:
              print("That was not a number")
        print(lst)
  listcount()

  yes = ["yes", "y"]
  no = ["no", "n"]
  yup = ["yes", "y"]
  nah = ["no", "n"]

  enteragain = input("Enter another number? yes/no")
  if enteragain in yes:
        print("Ok")
  elif enteragain in no:
        print("We'll try again")
        addtolist()

  runagain = input("Are those the numbers you wanted to enter?")
  if runagain in yes:
        print("Ok")
  elif runagain in no:
        print("We'll try again")
        addtolist()

addtolist()

Answer 1

I fiddled a little with it and instead of storing the list as a text file I decided to keep it in list form. Here is what I came up with at the end:

lst = list()
def addtolist():  #creates a function for adding numbers to the list
  def listcount():  #
        try:
              lst.append(int(input("Enter a number: ")))
        except ValueError:
              print("That was not a number")
              addtolist()
        print(lst)
  listcount()

  yes = ["yes", "y"]
  no = ["no", "n"]

  def playagain():
        enteragain = input("Enter another number? yes/no?... ")
        if enteragain in no:
              print("Ok!\n Calculating average.../n")
        elif enteragain in yes:
              print("Ok then!")
              addtolist()
        else:
              print("Please type either yes or no")
              playagain()
  playagain()

addtolist()

total = sum(lst)
numbers = len(lst)
average = total/numbers

print("The average of", lst, "is", average)