find the sum/mean of a list and find out when duplicated numbers are in a list

Question

I'm using python and I'm unable to find out how to get python to alert a user when he gives an integer as an input, that has already been entered. Also for some reason I am not able to find the sum of a list let alone the mean. Here is what I have so far tried. I want a user to be able to enter 10 integers.

value = raw_input ("Enter a number: ")
numbers = [(x) for x in value.split()]
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))
numbers.append (raw_input("Enter a number: "))

print sum(numbers)/len(numbers)

This allows a user to make a list and when I print the list, it comes out fine

Enter a number: 1
Enter a number: 2
Enter a number: 3
Enter a number: 4
Enter a number: 5
Enter a number: 6
Enter a number: 7
Enter a number: 8
Enter a number: 9
Enter a number: 8
>>> print numbers
['1', '2', '3', '4', '5', '6', '7', '8', '9', '8']

Now when I use this code to find the sum or even the mean.

print sum(numbers)/len(numbers)

After the user enters the 10 numbers, this comes out

Traceback (most recent call last):
  File "C:/Python27/need help.py", line 13, in <module>
    print sum(numbers)/ len (numbers)
TypeError: unsupported operand type(s) for +: 'int' and 'str'

also is there a way to alert the user when they have entered a duplicate number?

Please I really need help.

Answer 1

You haven't converted the input into integers. They are still strings.

Use this to convert them -

numbers = [int(i) for i in numbers]