Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 4 — Answers
Answer sheet with worked solutions for the Year 5 factors, multiples & primes worksheet.
Success TutoringWorksheetsAnswer sheetYear 5 · Mathematics · Factors, Multiples & PrimesYear 5 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 4 — Answers
Keep splitting each number into two factors until every branch ends in a prime. Write repeated factors with an index, e.g. 2 × 2 × 2 = 23.
1.Use a factor tree to write 385 as a product of prime factors in index form.
Answer: 5×7×11
- 385 = 5 × 77
- 77 = 7 × 11
- So 385 = 5 × 7 × 11 = 5 × 7 × 11
2.Which number has the prime factorisation 3 × 7 × 11?
Answer: 231
- 3 × 7 × 11 = 231
3.Use a factor tree to write 770 as a product of prime factors in index form.
Answer: 2×5×7×11
- 770 = 2 × 385
- 385 = 5 × 77
- 77 = 7 × 11
- So 770 = 2 × 5 × 7 × 11 = 2 × 5 × 7 × 11
4.Which number has the prime factorisation 5 × 7 × 11?
Answer: 385
- 5 × 7 × 11 = 385
5.Use a factor tree to write 550 as a product of prime factors in index form.
Answer: 2×52×11
- 550 = 2 × 275
- 275 = 5 × 55
- 55 = 5 × 11
- So 550 = 2 × 5 × 5 × 11 = 2 × 52 × 11
6.Which number has the prime factorisation 22 × 3 × 72?
Answer: 588
- 2 × 2 × 3 × 7 × 7 = 588
7.Use a factor tree to write 154 as a product of prime factors in index form.
Answer: 2×7×11
- 154 = 2 × 77
- 77 = 7 × 11
- So 154 = 2 × 7 × 11 = 2 × 7 × 11
8.Which number has the prime factorisation 5 × 112?
Answer: 605
- 5 × 11 × 11 = 605
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.