Year 7 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 4 — Answers
Answer sheet with worked solutions for the Year 7 factors, multiples & primes worksheet.
Success TutoringWorksheetsAnswer sheetYear 7 · Mathematics · Factors, Multiples & PrimesYear 7 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 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 2 × 3 × 11?
Answer: 66
- 2 × 3 × 11 = 66
3.Use a factor tree to write 165 as a product of prime factors in index form.
Answer: 3×5×11
- 165 = 3 × 55
- 55 = 5 × 11
- So 165 = 3 × 5 × 11 = 3 × 5 × 11
4.Which number has the prime factorisation 2 × 32 × 5 × 11?
Answer: 990
- 2 × 3 × 3 × 5 × 11 = 990
5.Use a factor tree to write 147 as a product of prime factors in index form.
Answer: 3×72
- 147 = 3 × 49
- 49 = 7 × 7
- So 147 = 3 × 7 × 7 = 3 × 72
6.Which number has the prime factorisation 2 × 3 × 5 × 7?
Answer: 210
- 2 × 3 × 5 × 7 = 210
7.Use a factor tree to write 90 as a product of prime factors in index form.
Answer: 2×32×5
- 90 = 2 × 45
- 45 = 3 × 15
- 15 = 3 × 5
- So 90 = 2 × 3 × 3 × 5 = 2 × 32 × 5
8.Which number has the prime factorisation 22 × 3 × 7 × 11?
Answer: 924
- 2 × 2 × 3 × 7 × 11 = 924
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.
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