Math With Mr DJ

Grade 6 · The Number System · 6.NS.B.4

GCF & LCM Worksheets

Free, printable, and ready to teach: a practice worksheet, homework, an exit ticket, and an answer key with step-by-step solutions — plus lesson slides you can edit. No sign-up needed.

First page of the gcf & lcm practice worksheet Open the practice worksheet

Download free

PDFs print on US Letter paper. Free for classroom and home use.

Watch: Prime Factorization Using a Factor Tree
Key idea

GCF of 21 and 35: 21 = 3×7, 35 = 5×7. Shared: 7. LCM of 6 and 10: the smallest number both divide into is 30.

Sample problems

  1. Find the GCF of 8 and 12.
  2. Find the GCF of 15 and 25.
  3. Find the LCM of 3 and 5.
  4. Find the LCM of 6 and 9.

Common mistakes to watch for

  • Answered 3 — stopped at a common factor without checking for a larger one. Or answered 36 (that’s the LCM).
  • Answered 24 (used 4 × 6 without reducing) or 2 (that’s the GCF).
  • Answered 6 — a real common factor, but not the greatest. List all the way up.

The answer key explains each one, so you can tell what a wrong answer means.

How to use this set

  1. Teach with the slides (about 15 minutes), or watch the video together.
  2. Practice with the worksheet. Questions climb from fluency to application to reasoning.
  3. Check understanding with the exit ticket, and send the homework home.
  4. Mark with the answer key — each answer shows the steps and the most likely mistake.

More Grade 6 worksheets

All Grade 6 →
Dividing Fractions6.NS.A.1 · Practice · Homework · Exit ticket · Answer key · Slides▶ Video lessonMulti-Digit Division6.NS.B.2 · Practice · Homework · Exit ticket · Answer key · Slides▶ Video lessonAdding & Subtracting Decimals6.NS.B.3 · Practice · Homework · Exit ticket · Answer key · SlidesMultiplying & Dividing Decimals6.NS.B.3 · Practice · Homework · Exit ticket · Answer key · Slides▶ Video lessonFactoring with the Distributive Property6.NS.B.4 · Practice · Homework · Exit ticket · Answer key · SlidesPositive & Negative Numbers6.NS.C.5 · Practice · Homework · Exit ticket · Answer key · Slides▶ Video lesson
Daily math puzzlesThree new puzzles every day, mild to spicy. Great as a warm-up. Step-by-step videosFree math lessons on YouTube from Mr DJ.

Get new worksheets first

New worksheets, videos, and free resources from Mr DJ — about once a month. No spam, ever.