Year 8 Prime Factorisation (Factor Trees) Worksheet — Level 1 — Practice Set 2 — Answers
Answer sheet with worked solutions for the Year 8 factors, multiples & primes worksheet.
Success TutoringWorksheetsAnswer sheetYear 8 · Mathematics · Factors, Multiples & PrimesYear 8 Prime Factorisation (Factor Trees) Worksheet — Level 1 — 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 45 as a product of prime factors.
Answer: 3×3×5
- 45 = 3 × 15
- 15 = 3 × 5
- So 45 = 3 × 3 × 5 = 32 × 5
2.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
3.Use a factor tree to write 18 as a product of prime factors.
Answer: 2×3×3
- 18 = 2 × 9
- 9 = 3 × 3
- So 18 = 2 × 3 × 3 = 2 × 32
4.Use a factor tree to write 20 as a product of prime factors.
Answer: 2×2×5
- 20 = 2 × 10
- 10 = 2 × 5
- So 20 = 2 × 2 × 5 = 22 × 5
5.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
6.Use a factor tree to write 30 as a product of prime factors.
Answer: 2×3×5
- 30 = 2 × 15
- 15 = 3 × 5
- So 30 = 2 × 3 × 5
7.Use a factor tree to write 12 as a product of prime factors.
Answer: 2×2×3
- 12 = 2 × 6
- 6 = 2 × 3
- So 12 = 2 × 2 × 3 = 22 × 3
8.Use a factor tree to write 75 as a product of prime factors.
Answer: 3×5×5
- 75 = 3 × 25
- 25 = 5 × 5
- So 75 = 3 × 5 × 5 = 3 × 52
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
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