Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Python Basics (Retired) Putting the "Fun" Back in "Function" Functions

Adding a list - python

How would I add all the numbers in a list, within a function

functions.py
# add_list([1, 2, 3]) should return 6
def add_list(lists):
  for numb in lists:
    numb[0] + numb[1] + numb[2]
# summarize([1, 2, 3]) should return "The sum of [1, 2, 3] is 6."
# Note: both functions will only take *one* argument each.

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,468 Points

Hi Michael, you're very close. This missing part is to accumulate the total as the for loop runs:

def add_list(lists):
    # initialize total to 0
    total = 0
    for numb in lists:
        # Add numb to total
        total += numb
    # Remember to return a value from the function
    return total

Reminder: total += numb is equivalent to total = total + numb