Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 2 — Practice Set 2 — Answers
Answer sheet with worked solutions for the Year 5 factors, multiples & primes worksheet.
Success TutoringWorksheetsAnswer sheetYear 5 · Mathematics · Factors, Multiples & PrimesYear 5 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 252 as a product of prime factors.
Answer: 2×2×3×3×7
- 252 = 2 × 126
- 126 = 2 × 63
- 63 = 3 × 21
- 21 = 3 × 7
- So 252 = 2 × 2 × 3 × 3 × 7 = 22 × 32 × 7
2.Use a factor tree to write 42 as a product of prime factors.
Answer: 2×3×7
- 42 = 2 × 21
- 21 = 3 × 7
- So 42 = 2 × 3 × 7
3.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
4.Which number has the prime factorisation 2 × 3 × 7?
Answer: 42
- 2 × 3 × 7 = 42
5.Use a factor tree to write 126 as a product of prime factors.
Answer: 2×3×3×7
- 126 = 2 × 63
- 63 = 3 × 21
- 21 = 3 × 7
- So 126 = 2 × 3 × 3 × 7 = 2 × 32 × 7
6.Use a factor tree to write 98 as a product of prime factors.
Answer: 2×7×7
- 98 = 2 × 49
- 49 = 7 × 7
- So 98 = 2 × 7 × 7 = 2 × 72
7.Use a factor tree to write 294 as a product of prime factors.
Answer: 2×3×7×7
- 294 = 2 × 147
- 147 = 3 × 49
- 49 = 7 × 7
- So 294 = 2 × 3 × 7 × 7 = 2 × 3 × 72
8.Which number has the prime factorisation 3 × 5 × 7?
Answer: 105
- 3 × 5 × 7 = 105
Marking tips
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