Year 7 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 4 — 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 3 — Practice Set 4 — Answers
Keep splitting each number into two factors until every branch ends in a prime. Write repeated factors with an index, e.g. 2 × 2 × 2 = 23.
1.Use a factor tree to write 126 as a product of prime factors in index form.
Answer: 2×32×7
- 126 = 2 × 63
- 63 = 3 × 21
- 21 = 3 × 7
- So 126 = 2 × 3 × 3 × 7 = 2 × 32 × 7
2.Which number has the prime factorisation 22 × 3 × 7 × 11?
Answer: 924
- 2 × 2 × 3 × 7 × 11 = 924
3.Use a factor tree to write 882 as a product of prime factors in index form.
Answer: 2×32×72
- 882 = 2 × 441
- 441 = 3 × 147
- 147 = 3 × 49
- 49 = 7 × 7
- So 882 = 2 × 3 × 3 × 7 × 7 = 2 × 32 × 72
4.Which number has the prime factorisation 22 × 3 × 11?
Answer: 132
- 2 × 2 × 3 × 11 = 132
5.Use a factor tree to write 588 as a product of prime factors in index form.
Answer: 22×3×72
- 588 = 2 × 294
- 294 = 2 × 147
- 147 = 3 × 49
- 49 = 7 × 7
- So 588 = 2 × 2 × 3 × 7 × 7 = 22 × 3 × 72
6.Which number has the prime factorisation 3 × 5 × 11?
Answer: 165
- 3 × 5 × 11 = 165
7.Use a factor tree to write 420 as a product of prime factors in index form.
Answer: 22×3×5×7
- 420 = 2 × 210
- 210 = 2 × 105
- 105 = 3 × 35
- 35 = 5 × 7
- So 420 = 2 × 2 × 3 × 5 × 7 = 22 × 3 × 5 × 7
8.Which number has the prime factorisation 72 × 11?
Answer: 539
- 7 × 7 × 11 = 539
Marking tips
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