Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 3 — 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 — 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 539 as a product of prime factors in index form.
Answer: 72×11
- 539 = 7 × 77
- 77 = 7 × 11
- So 539 = 7 × 7 × 11 = 72 × 11
2.Which number has the prime factorisation 3 × 72?
Answer: 147
- 3 × 7 × 7 = 147
3.Use a factor tree to write 450 as a product of prime factors in index form.
Answer: 2×32×52
- 450 = 2 × 225
- 225 = 3 × 75
- 75 = 3 × 25
- 25 = 5 × 5
- So 450 = 2 × 3 × 3 × 5 × 5 = 2 × 32 × 52
4.Which number has the prime factorisation 2 × 5 × 72?
Answer: 490
- 2 × 5 × 7 × 7 = 490
5.Use a factor tree to write 308 as a product of prime factors in index form.
Answer: 22×7×11
- 308 = 2 × 154
- 154 = 2 × 77
- 77 = 7 × 11
- So 308 = 2 × 2 × 7 × 11 = 22 × 7 × 11
6.Which number has the prime factorisation 22 × 3 × 5 × 11?
Answer: 660
- 2 × 2 × 3 × 5 × 11 = 660
7.Use a factor tree to write 630 as a product of prime factors in index form.
Answer: 2×32×5×7
- 630 = 2 × 315
- 315 = 3 × 105
- 105 = 3 × 35
- 35 = 5 × 7
- So 630 = 2 × 3 × 3 × 5 × 7 = 2 × 32 × 5 × 7
8.Which number has the prime factorisation 32 × 7 × 11?
Answer: 693
- 3 × 3 × 7 × 11 = 693
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.