Year 7 Prime Factorisation (Factor Trees) Worksheet — Level 3 — 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 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 750 as a product of prime factors in index form.
Answer: 2×3×53
- 750 = 2 × 375
- 375 = 3 × 125
- 125 = 5 × 25
- 25 = 5 × 5
- So 750 = 2 × 3 × 5 × 5 × 5 = 2 × 3 × 53
2.Which number has the prime factorisation 23 × 3 × 11?
Answer: 264
- 2 × 2 × 2 × 3 × 11 = 264
3.Use a factor tree to write 165 as a product of prime factors in index form.
Answer: 3×5×11
- 165 = 3 × 55
- 55 = 5 × 11
- So 165 = 3 × 5 × 11 = 3 × 5 × 11
4.Which number has the prime factorisation 23 × 3 × 5 × 7?
Answer: 840
- 2 × 2 × 2 × 3 × 5 × 7 = 840
5.Use a factor tree to write 63 as a product of prime factors in index form.
Answer: 32×7
- 63 = 3 × 21
- 21 = 3 × 7
- So 63 = 3 × 3 × 7 = 32 × 7
6.Which number has the prime factorisation 23 × 3 × 7?
Answer: 168
- 2 × 2 × 2 × 3 × 7 = 168
7.Use a factor tree to write 315 as a product of prime factors in index form.
Answer: 32×5×7
- 315 = 3 × 105
- 105 = 3 × 35
- 35 = 5 × 7
- So 315 = 3 × 3 × 5 × 7 = 32 × 5 × 7
8.Which number has the prime factorisation 3 × 5 × 7?
Answer: 105
- 3 × 5 × 7 = 105
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.