✨ Earn college credits in Cybersecurity, JS, HTML, CSS and Python

🤑 Join the Treehouse affiliate program and earn 25% recurring commission!

New No-Code Track! 🚀start learning today!

🌟 Dreaming of a bright future? 🎓 Ask about the Treehouse Scholarship program! 🚀

✨ Earn college credits in Cybersecurity, JS, HTML, CSS and Python

🤑 Join the Treehouse affiliate program and earn 25% recurring commission!

  • Treehouse Logo
  • Plans
    Chevron
    • For Individuals
    • For Businesses
    • For Schools
    • For Libraries
    • For Military
  • Library
    Chevron
    • All Courses
    • Tracks
    • College Credit
  • Techdegree
    Chevron
    • Overview
    • Front End Development
    • Full Stack JavaScript
    • Data Analysis
    • UX Design
    • Python
  • Community
    Chevron
    • Code Adventures
    • Discord
    • Forum
    • Success Stories
    • Treehouse Links
    • 100 Days of Code
  • Resources
    Chevron
    • Career Toolbox
    • CodeForward
    • Free Treehouse Near Me
    • Jobs
    • Blog
    • Support
    • About
  • For Individuals For Businesses For Schools For Libraries For Military
  • All Courses Tracks College Credit
  • Overview Front End Web Development Full Stack JavaScript Python Development Data Analysis UX Design
  • Code Adventures Discord Forum Success Stories Treehouse Links 100 Days of Code
  • Career Toolbox CodeForward Free Treehouse Near Me Jobs Blog Support About
  • Sign In
  • Free Trial
Instagram Twitter Facebook YouTube LinkedIn
    • Newest
      • Newest
      • Active
      • Unanswered
      • Featured
    • All Topics
      • All Topics
      • • General Discussion
      • • AI
      • • Android
      • • APIs
      • • Coding for Kids
      • • College Credit
      • • Computer Science
      • • CSS
      • • Data Analysis
      • • Databases
      • • Design
      • • Development Tools
      • • Digital Literacy
      • • Game Development
      • • Go Language
      • • HTML
      • • Java
      • • JavaScript
      • • Learning Resources
      • • Machine Learning
      • • No-Code
      • • PHP
      • • Professional Growth
      • • Python
      • • Quality Assurance
      • • React
      • • Ruby
      • • Security
      • • Swift
    • Showing results for:
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists
    • Close
  • Leah Kelly
    Leah Kelly
    4,141 Points

    What is sum?

    Posted on Nov 11, 2021 by Leah Kelly
    Leah Kelly
    4,141 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • aaron roberts
    aaron roberts
    2,004 Points

    how to .remove from a multidimensional list?

    Posted on Feb 24, 2021 by aaron roberts
    aaron roberts
    2,004 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Luke Tate
    PLUS
    Luke Tate
    Courses Plus Student 2,256 Points

    Why does the "sum" have no definition? Is it built in code?

    Posted on Jul 17, 2020 by Luke Tate
    Luke Tate
    Courses Plus Student 2,256 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Benyamin Kohanchi
    PLUS
    Benyamin Kohanchi
    Courses Plus Student 2,342 Points

    what does "week" in sum(week) mean in Craig's code?

    Posted on Jul 9, 2020 by Benyamin Kohanchi
    Benyamin Kohanchi
    Courses Plus Student 2,342 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Jeremy Hall
    Jeremy Hall
    2,048 Points

    How big of a list in Real World Applications would be considered too much?

    Posted on Jun 15, 2020 by Jeremy Hall
    Jeremy Hall
    2,048 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • cory woods
    cory woods
    2,568 Points

    week_number <--- is that a variable?

    Posted on May 8, 2020 by cory woods
    cory woods
    2,568 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Aizah Sadiq
    Aizah Sadiq
    2,435 Points

    I'm getting an invalid syntax

    Posted on Apr 2, 2020 by Aizah Sadiq
    Aizah Sadiq
    2,435 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Aizah Sadiq
    Aizah Sadiq
    2,435 Points

    Why do we put week_number += 1

    Posted on Apr 2, 2020 by Aizah Sadiq
    Aizah Sadiq
    2,435 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Ryan McGuire
    Ryan McGuire
    3,758 Points

    How would we iterate across the days if we wanted to sum up the expenses from all Mondays?

    Posted on Dec 9, 2019 by Ryan McGuire
    Ryan McGuire
    3,758 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Ankush Sharma
    Ankush Sharma
    844 Points

    Why we put increment in the end of loop.It is necessary?

    Posted on Nov 2, 2019 by Ankush Sharma
    Ankush Sharma
    844 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Charan sai
    PLUS
    Charan sai
    Courses Plus Student 797 Points

    How to multiply two multidimensional lists like multiplication of matrices??

    Posted on Oct 16, 2019 by Charan sai
    Charan sai
    Courses Plus Student 797 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Federico Lemaire
    Federico Lemaire
    8,423 Points

    Help with two things :)

    Posted on Oct 15, 2019 by Federico Lemaire
    Federico Lemaire
    8,423 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

  • Kayc M
    Kayc M
    12,593 Points

    What if I wanted to sum it all together after iterating them?

    Posted on Mar 6, 2019 by Kayc M
    Kayc M
    12,593 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Iulia Maria Lungu
    Iulia Maria Lungu
    19,302 Points

    I wonder how this ad got into the quiz page

    Posted on Oct 31, 2018 by Iulia Maria Lungu
    Iulia Maria Lungu
    19,302 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    3 Answers

  • Alexander Salako
    Alexander Salako
    2,434 Points

    problem iterating through the travel expenses list

    Posted on Sep 21, 2018 by Alexander Salako
    Alexander Salako
    2,434 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Devdatta Pattnaik
    Devdatta Pattnaik
    101 Points

    Freelancing

    Posted on Aug 19, 2018 by Devdatta Pattnaik
    Devdatta Pattnaik
    101 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Eswar Ambati
    Eswar Ambati
    890 Points

    I do not understand the code at 5:48

    Posted on Jul 16, 2018 by Eswar Ambati
    Eswar Ambati
    890 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Magnus Lindberg Christensen
    Magnus Lindberg Christensen
    2,231 Points

    Multidimensional Lists

    Posted on Jun 12, 2018 by Magnus Lindberg Christensen
    Magnus Lindberg Christensen
    2,231 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    2 Answers

  • Mathew Yangang
    Mathew Yangang
    4,433 Points

    copy and paste

    Posted on Jun 7, 2018 by Mathew Yangang
    Mathew Yangang
    4,433 Points
    • Python
    • Introducing Lists
    • Using Lists
    • Multidimensional Lists

    1 Answer

Posting to the forum is only allowed for members with active accounts.
Please sign in or sign up to post.

    Treehouse

  • About
  • Blog
  • Careers
  • Community
  • Stories
  • Shop
  • Contact
  • Gift Card

See Full Catalogue

Techdegree

  • Front End Web Development
  • Full Stack JavaScript
  • Python Development
  • Data Analysis
  • UX Design

Tracks

  • Learn to Code for Beginners
  • Beginning Python
  • Beginning SQL
  • Beginning Java
  • ...see more

Courses

  • JavaScript Basics
  • Intro to HTML & CSS
  • Python Basics
  • CSS Layout
  • ...see more

Explore

  • Plans
  • Affiliates
  • Perks
  • Free Treehouse Near Me
  • Treehouse for Libraries
  • Treehouse for Businesses
  • Twitter
  • YouTube
  • Facebook
  • LinkedIn
  • Instagram
Terms & Conditions | Privacy

© 2025 Treehouse Island, Inc.