These prime factorization worksheets are generated rather than scanned, which means you can print a different sheet every day of the week without paying for a subscription or running out of practice. A typical problem from the sheet in front of you is Prime factorization of 70, which works out to 2 × 5 × 7; another is Prime factorization of 112, giving 2 × 2 × 2 × 2 × 7.
‘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.
This sheet uses numbers from 12 to 120, small enough to be listed out and large enough to make listing a slow method, and a typical line looks like Prime factorization of 14.
Because each sheet is new, the child cannot recall the answer from having done the same pair yesterday.
Prime factorisation is the general tool: break both numbers down, take the shared primes for the factor and all of them for the multiple.
Divisibility rules are worth memorising alongside this — even, digit sum divisible by three, ends in zero or five — because they turn Prime factorization of 112 from a search into a glance.
These prime factorization worksheets are commonly aligned with the number system strand for grades 5 and 6, and the skill appears in most curricula somewhere around this point.
| # | Problem | Answer | What to check |
|---|---|---|---|
| 1 | Prime factorization of 70 = | 2 × 5 × 7 | Watch for: leaving the factorisation incomplete |
| 2 | Prime factorization of 112 = | 2 × 2 × 2 × 2 × 7 | Check: missing one in a factor list |
| 3 | Prime factorization of 32 = | 2 × 2 × 2 × 2 × 2 | Look at: swapping factor and multiple |
| 4 | Prime factorization of 102 = | 2 × 3 × 17 | Ask about: multiplying the two numbers for the lcm |
| 5 | Prime factorization of 14 = | 2 × 7 | Watch for: treating a prime as having no factors |
| 6 | Prime factorization of 60 = | 2 × 2 × 3 × 5 | Check: stopping at a common factor rather than the greatest |
Work Prime factorization of 102 out loud as a demonstration. It gives 2 × 3 × 17. Children who hear Prime factorization of 102 reasoned through once at the start of a session make noticeably fewer errors in the ten minutes that follow.
Here is one worked through. Prime factorization of 112 gives 2 × 2 × 2 × 2 × 7. If your child arrives somewhere other than 2 × 2 × 2 × 2 × 7 on Prime factorization of 112, look at the working rather than the answer: nearly every wrong result comes from a skipped step, not an unknown fact.
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.
Keys are produced by the same code that produces the questions, so a mismatch between question and answer is not possible on these sheets.
To save these 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.
If the problems look cramped, drop the count from 20 to a smaller number before printing these prime factorization worksheets; the font stays the same size and the spacing opens up.
One sheet of prime factorization worksheets a day for two weeks will tell you more about where a child working at this level actually stands than any single long assessment.
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