Use this page when you want 6th grade prime factorization worksheets in the next thirty seconds: choose how many problems you want, press print, and the answer key comes out on its own page behind the worksheet. Right now the generator is set to problems such as Prime factorization of 33 (answer 3 × 11) and Prime factorization of 21 (answer 3 × 7); press the button again and the numbers change while the skill stays the same.
‘New set of problems’ opens the generator in its own tab. There you can change the problem count and turn the answer key on or off. ‘Print or save as PDF’ opens the print dialog — choose Save as PDF in the printer list to keep the file. The sheet fits US Letter and A4, and the answer key prints on its own page.
Because each sheet is new, the child cannot recall the answer from having done the same pair yesterday.
Factors and multiples pull in opposite directions: factors divide into a number, multiples are built from it. A question like Prime factorization of 33 answers 3 × 11, and knowing which direction the question is asking is half the battle.
The greatest common factor is what simplifies a fraction; the lowest common multiple is what gives it a common denominator. Both jobs turn up constantly, which is why this topic is worth being fast at.
Divisibility rules are worth memorising alongside this — even, digit sum divisible by three, ends in zero or five — because they turn Prime factorization of 21 from a search into a glance.
Work of this kind is commonly aligned with the number system strand for grades 5 and 6; schools outside the US meet the same skill at roughly the same age, which is why these 6th grade prime factorization worksheets travel well.
| # | Problem | Answer | What to check |
|---|---|---|---|
| 1 | Prime factorization of 33 = | 3 × 11 | Watch for: multiplying the two numbers for the lcm |
| 2 | Prime factorization of 21 = | 3 × 7 | Check: treating a prime as having no factors |
| 3 | Prime factorization of 105 = | 3 × 5 × 7 | Look at: missing one in a factor list |
| 4 | Prime factorization of 20 = | 2 × 2 × 5 | Ask about: stopping at a common factor rather than the greatest |
| 5 | Prime factorization of 34 = | 2 × 17 | Watch for: leaving the factorisation incomplete |
| 6 | Prime factorization of 50 = | 2 × 5 × 5 | Check: swapping factor and multiple |
Here is one worked through. Prime factorization of 21 gives 3 × 7. If your child arrives somewhere other than 3 × 7 on Prime factorization of 21, look at the working rather than the answer: nearly every wrong result comes from a skipped step, not an unknown fact.
Take the first problem on the sheet as it stands, Prime factorization of 33. Work Prime factorization of 33 out on paper rather than in your head the first few times, say each step aloud, and check the result against 3 × 11 on the key before moving on.
The key prints on its own page by default. Uncheck the answer-key box before printing if you would rather keep it back and mark the sheet yourself.
Every generated sheet carries its own key on a separate printed page, which lets a child self-mark without seeing the answers while they work.
The sheet is laid out to fit one page on both US Letter and A4. Leave the browser scaling at 100% and turn headers and footers off, and the 20 problems land inside the margins on either paper size.
To save these 6th grade prime factorization worksheets instead of printing them, choose 'Save as PDF' in the printer list. You get the worksheet and the answer key as a single PDF, on Letter or A4 depending on your printer settings.
One sheet of 6th grade prime factorization worksheets a day for two weeks will tell you more about where a 6th grader actually stands than any single long assessment.
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Free printable math worksheets from a working math academy director in Korea. Problems come from our own code, not from a published workbook. Every sheet prints on US Letter or A4 with its answer key. All worksheets · Worksheet generator · Korean site
Last updated: 2026-09-13