Year 7 Prime Factorisation (Factor Trees) Worksheet — Level 2 — Practice Set 3 — 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 3 — 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 300 as a product of prime factors.
Answer: 2×2×3×5×5
- 300 = 2 × 150
- 150 = 2 × 75
- 75 = 3 × 25
- 25 = 5 × 5
- So 300 = 2 × 2 × 3 × 5 × 5 = 22 × 3 × 52
3.Use a factor tree to write 147 as a product of prime factors.
Answer: 3×7×7
- 147 = 3 × 49
- 49 = 7 × 7
- So 147 = 3 × 7 × 7 = 3 × 72
4.Which number has the prime factorisation 2 × 3 × 5?
Answer: 30
- 2 × 3 × 5 = 30
5.Use a factor tree to write 150 as a product of prime factors.
Answer: 2×3×5×5
- 150 = 2 × 75
- 75 = 3 × 25
- 25 = 5 × 5
- So 150 = 2 × 3 × 5 × 5 = 2 × 3 × 52
6.Use a factor tree to write 140 as a product of prime factors.
Answer: 2×2×5×7
- 140 = 2 × 70
- 70 = 2 × 35
- 35 = 5 × 7
- So 140 = 2 × 2 × 5 × 7 = 22 × 5 × 7
7.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
8.Which number has the prime factorisation 5 × 72?
Answer: 245
- 5 × 7 × 7 = 245
Marking tips
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