Worksheets · Pre-Algebra

Greatest common factor worksheet

Break each number into its prime factors and take everything they share. What you are left with is the largest number that goes into all of them.

Select your difficulty

Pick more than one for a sheet that mixes them.

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Greatest Common Factor

Date Period

Find the greatest common factor.

  1. Find the GCF of 77 and 88
  2. Find the GCF of 108 and 84
  3. Find the GCF of 99 and 88
  4. Find the GCF of 96 and 84
  5. Find the GCF of 70 and 80
  6. Find the GCF of 72 and 81
  7. Find the GCF of 99 and 77
  8. Find the GCF of 81 and 72
  9. Find the GCF of 84 and 96
  10. Find the GCF of 63 and 81
  11. Find the GCF of 84 and 108
  12. Find the GCF of 88 and 77
  13. Find the GCF of 81 and 63
  14. Find the GCF of 96 and 108
  15. Find the GCF of 77 and 99
  16. Find the GCF of 72 and 63
  17. Find the GCF of 90 and 70
  18. Find the GCF of 63 and 72
  19. Find the GCF of 90 and 80
  20. Find the GCF of 70 and 90

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

Sigma Prep · sigmaprep.io/worksheets

Name

Greatest Common FactorAnswer keyVersion 1

Date Period

Find the greatest common factor.

  1. Find the GCF of 77 and 8811
  2. Find the GCF of 108 and 8412
  3. Find the GCF of 99 and 8811
  4. Find the GCF of 96 and 8412
  5. Find the GCF of 70 and 8010
  6. Find the GCF of 72 and 819
  7. Find the GCF of 99 and 7711
  8. Find the GCF of 81 and 729
  9. Find the GCF of 84 and 9612
  10. Find the GCF of 63 and 819
  11. Find the GCF of 84 and 10812
  12. Find the GCF of 88 and 7711
  13. Find the GCF of 81 and 639
  14. Find the GCF of 96 and 10812
  15. Find the GCF of 77 and 9911
  16. Find the GCF of 72 and 639
  17. Find the GCF of 90 and 7010
  18. Find the GCF of 63 and 729
  19. Find the GCF of 90 and 8010
  20. Find the GCF of 70 and 9010

Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep

How to do these

The GCF of 24 and 36

  1. 24 is 2 x 2 x 2 x 3.
  2. 36 is 2 x 2 x 3 x 3.
  3. They share 2 x 2 x 3.

The answer is 12.

Where students go wrong

Stopping at a common factor rather than the greatest one. Four divides both 24 and 36, but so does 12, and only the largest counts.

Also called GCF, highest common factor, HCF or greatest common divisor.

Questions about these worksheets

Yes. Every greatest common factor sheet is free to print and free to download as a PDF. There is no account to make, no email to hand over and no limit on how many you take.

Yes. The answer key prints on a second page, and you can choose whether it shows each question beside its answer or just the answers in a list.

Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.

Pre-Algebra is usually taken around 7th or 8th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.

Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.

That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the greatest common factor questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.

Yes. There are two levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.

Stopping at a common factor rather than the greatest one. Four divides both 24 and 36, but so does 12, and only the largest counts.