Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 2 — 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 2 — 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 490 as a product of prime factors in index form.
Answer: 2×5×72
- 490 = 2 × 245
- 245 = 5 × 49
- 49 = 7 × 7
- So 490 = 2 × 5 × 7 × 7 = 2 × 5 × 72
2.Which number has the prime factorisation 2 × 5 × 7 × 11?
Answer: 770
- 2 × 5 × 7 × 11 = 770
3.Use a factor tree to write 70 as a product of prime factors in index form.
Answer: 2×5×7
- 70 = 2 × 35
- 35 = 5 × 7
- So 70 = 2 × 5 × 7 = 2 × 5 × 7
4.Which number has the prime factorisation 22 × 3 × 5?
Answer: 60
- 2 × 2 × 3 × 5 = 60
5.Use a factor tree to write 110 as a product of prime factors in index form.
Answer: 2×5×11
- 110 = 2 × 55
- 55 = 5 × 11
- So 110 = 2 × 5 × 11 = 2 × 5 × 11
6.Which number has the prime factorisation 23 × 32 × 7?
Answer: 504
- 2 × 2 × 2 × 3 × 3 × 7 = 504
7.Use a factor tree to write 75 as a product of prime factors in index form.
Answer: 3×52
- 75 = 3 × 25
- 25 = 5 × 5
- So 75 = 3 × 5 × 5 = 3 × 52
8.Which number has the prime factorisation 2 × 33 × 5?
Answer: 270
- 2 × 3 × 3 × 3 × 5 = 270
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.