Year 8 Prime Factorisation (Factor Trees) Worksheet — Level 2 — 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 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 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 120 as a product of prime factors.
Answer: 2×2×2×3×5
- 120 = 2 × 60
- 60 = 2 × 30
- 30 = 2 × 15
- 15 = 3 × 5
- So 120 = 2 × 2 × 2 × 3 × 5 = 23 × 3 × 5
3.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
4.Which number has the prime factorisation 3 × 72?
Answer: 147
- 3 × 7 × 7 = 147
5.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
6.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
7.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
8.Which number has the prime factorisation 22 × 3 × 7?
Answer: 84
- 2 × 2 × 3 × 7 = 84
Marking tips
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