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Worksheets›Grade 6›Number system›Greatest common factor

Greatest Common Factor Worksheets

Free printable worksheets with answer keys. Pick a level, preview the questions, then open the sheet to swap or delete any single question.

Grade 6CCSS 6.NS.B.4Answer key includedPDF · Print
Open in generatorStart with an easy sheet

Easy: Two numbers up to 30

  1. 1.GCF(10, 4) =
  2. 2.GCF(25, 20) =
  3. 3.GCF(10, 25) =
  4. 4.GCF(6, 8) =
  5. 5.GCF(8, 10) =
  6. 6.GCF(8, 12) =
Preview shows 6 of 12 questions. Every sheet is new; open it to change any question.

Worksheet variations

The greatest common factor is the largest number that divides each number evenly. Listing factors or using prime factorization both work.

EasyGCF(5, 15) =Two numbers up to 30MediumGCF(70, 50) =Two numbers up to 100HardGCF(100, 70, 10) =Three numbers up to 120

How to solve it: a worked example

Find the greatest common factor (GCF).

  1. StartGCF(8, 4) =
  2. Then8 = 23
  3. Then4 = 22
  4. Multiply the shared prime factorsGCF = 4
  5. Answer4

Common mistakes to watch for

  • Giving the least common multiple instead of the greatest common factor.
  • Stopping at a common factor that is not the greatest.
  • Using primes that appear in only one of the numbers.

Tip: tick “Step-by-step answer key” in the generator to print each step for marking.

Related worksheets

Dividing fractionsAdding & subtracting decimalsMultiplying decimalsDividing decimalsLeast common multiple

FAQ

What is the GCF used for?

Simplifying fractions and factoring expressions such as 12x + 18 = 6(2x + 3).

Is every worksheet different?

Yes. Numbers are generated each time, and the answer key is calculated for that sheet. Swap any single question and its answer updates too.

Can I mix greatest common factor with other skills?

Yes. In the generator, add more skills; each gets its own section on the sheet with its own instructions.

Is it free to print?

Yes. Generating and printing from the browser is free with no sign-up. PDF downloads need a free account.