Year 8 Prime Factorisation (Factor Trees) Worksheet — Level 3 — 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 3 — Practice Set 2 — 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 110 as a product of prime factors in index form.
Answer: 2×5×11
- 110 = 2 × 55
- 55 = 5 × 11
- So 110 = 2 × 5 × 11 = 2 × 5 × 11
2.Which number has the prime factorisation 22 × 7 × 11?
Answer: 308
- 2 × 2 × 7 × 11 = 308
3.Use a factor tree to write 605 as a product of prime factors in index form.
Answer: 5×112
- 605 = 5 × 121
- 121 = 11 × 11
- So 605 = 5 × 11 × 11 = 5 × 112
4.Which number has the prime factorisation 3 × 112?
Answer: 363
- 3 × 11 × 11 = 363
5.Use a factor tree to write 105 as a product of prime factors in index form.
Answer: 3×5×7
- 105 = 3 × 35
- 35 = 5 × 7
- So 105 = 3 × 5 × 7 = 3 × 5 × 7
6.Which number has the prime factorisation 2 × 5 × 7 × 11?
Answer: 770
- 2 × 5 × 7 × 11 = 770
7.Use a factor tree to write 972 as a product of prime factors in index form.
Answer: 22×35
- 972 = 2 × 486
- 486 = 2 × 243
- 243 = 3 × 81
- 81 = 3 × 27
- 27 = 3 × 9
- 9 = 3 × 3
- So 972 = 2 × 2 × 3 × 3 × 3 × 3 × 3 = 22 × 35
8.Which number has the prime factorisation 32 × 5 × 7?
Answer: 315
- 3 × 3 × 5 × 7 = 315
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.