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 210 as a product of prime factors.
Answer: 2×3×5×7
- 210 = 2 × 105
- 105 = 3 × 35
- 35 = 5 × 7
- So 210 = 2 × 3 × 5 × 7
2.Use a factor tree to write 189 as a product of prime factors.
Answer: 3×3×3×7
- 189 = 3 × 63
- 63 = 3 × 21
- 21 = 3 × 7
- So 189 = 3 × 3 × 3 × 7 = 33 × 7
3.Use a factor tree to write 245 as a product of prime factors.
Answer: 5×7×7
- 245 = 5 × 49
- 49 = 7 × 7
- So 245 = 5 × 7 × 7 = 5 × 72
4.Which number has the prime factorisation 22 × 3 × 5?
Answer: 60
- 2 × 2 × 3 × 5 = 60
5.Use a factor tree to write 100 as a product of prime factors.
Answer: 2×2×5×5
- 100 = 2 × 50
- 50 = 2 × 25
- 25 = 5 × 5
- So 100 = 2 × 2 × 5 × 5 = 22 × 52
6.Use a factor tree to write 50 as a product of prime factors.
Answer: 2×5×5
- 50 = 2 × 25
- 25 = 5 × 5
- So 50 = 2 × 5 × 5 = 2 × 52
7.Use a factor tree to write 84 as a product of prime factors.
Answer: 2×2×3×7
- 84 = 2 × 42
- 42 = 2 × 21
- 21 = 3 × 7
- So 84 = 2 × 2 × 3 × 7 = 22 × 3 × 7
8.Which number has the prime factorisation 2 × 3 × 5 × 7?
Answer: 210
- 2 × 3 × 5 × 7 = 210
Marking tips
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