6th grade GCF & LCM worksheets

GCF and LCM worksheets give your child practice finding the greatest common factor of pairs up to 100 and the least common multiple of pairs up to 12, the skill 6th grade uses to factor expressions and add unlike fractions.

Free printable PDF worksheet, aligned to Common Core 6.NS.B.4.

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The kind of problems you'll get

Find the GCF or LCM of each pair.

  1. Find the LCM of 2 and 8.

    Answer: 8

  2. Find the GCF of 21 and 26.
  3. Find the LCM of 6 and 10.

Every print pulls a fresh set of problems at this level, so a make-up test or a second sibling never gets the same sheet.

What's on each sheet

Every version prints on US Letter or A4, with its answer key on the last page.

How to teach this

For GCF, list each number's factor pairs and circle the biggest factor they share. For LCM, count by each number aloud and stop at the first match: 4, 8, 12 meets 6, 12. Keep the two straight with a size check: the GCF divides in, the LCM holds both.

Watch for: GCF and LCM swap in kids' heads. The greatest common factor is never bigger than your numbers, and the least common multiple is never smaller. Multiplying the two numbers always gives the LCM. 4 × 6 is 24, but the least common multiple of 4 and 6 is 12.

Common questions about GCF & LCM

How big are the numbers?
GCF pairs go up to 100 and LCM pairs stay at 12 or below, matching the 6th grade standard. Every print draws a new set of pairs.
Why do GCF and LCM share one worksheet?
Because telling them apart is most of the skill. Mixing the two question types on one sheet makes your child read the question before reaching for a method.

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Aligned to Common Core 6.NS.B.4. Reviewed by the One more sheet curriculum team. Content version 123, updated July 2026.