Year 7 Prime Factorisation (Factor Trees) Worksheet — Level 2 — Practice Set 2 — 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 2 — Practice Set 2 — Answers
Keep splitting each number into two factors until every branch ends in a prime. Write the primes from smallest to largest.
1.Use a factor tree to write 40 as a product of prime factors.
Answer: 2×2×2×5
- 40 = 2 × 20
- 20 = 2 × 10
- 10 = 2 × 5
- So 40 = 2 × 2 × 2 × 5 = 23 × 5
2.Use a factor tree to write 135 as a product of prime factors.
Answer: 3×3×3×5
- 135 = 3 × 45
- 45 = 3 × 15
- 15 = 3 × 5
- So 135 = 3 × 3 × 3 × 5 = 33 × 5
3.Use a factor tree to write 196 as a product of prime factors.
Answer: 2×2×7×7
- 196 = 2 × 98
- 98 = 2 × 49
- 49 = 7 × 7
- So 196 = 2 × 2 × 7 × 7 = 22 × 72
4.Which number has the prime factorisation 23 × 5 × 7?
Answer: 280
- 2 × 2 × 2 × 5 × 7 = 280
5.Use a factor tree to write 60 as a product of prime factors.
Answer: 2×2×3×5
- 60 = 2 × 30
- 30 = 2 × 15
- 15 = 3 × 5
- So 60 = 2 × 2 × 3 × 5 = 22 × 3 × 5
6.Use a factor tree to write 280 as a product of prime factors.
Answer: 2×2×2×5×7
- 280 = 2 × 140
- 140 = 2 × 70
- 70 = 2 × 35
- 35 = 5 × 7
- So 280 = 2 × 2 × 2 × 5 × 7 = 23 × 5 × 7
7.Use a factor tree to write 105 as a product of prime factors.
Answer: 3×5×7
- 105 = 3 × 35
- 35 = 5 × 7
- So 105 = 3 × 5 × 7
8.Which number has the prime factorisation 2 × 3 × 5 × 7?
Answer: 210
- 2 × 3 × 5 × 7 = 210
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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