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 308 as a product of prime factors in index form.
Answer: 22×7×11
- 308 = 2 × 154
- 154 = 2 × 77
- 77 = 7 × 11
- So 308 = 2 × 2 × 7 × 11 = 22 × 7 × 11
2.Which number has the prime factorisation 3 × 52 × 11?
Answer: 825
- 3 × 5 × 5 × 11 = 825
3.Use a factor tree to write 726 as a product of prime factors in index form.
Answer: 2×3×112
- 726 = 2 × 363
- 363 = 3 × 121
- 121 = 11 × 11
- So 726 = 2 × 3 × 11 × 11 = 2 × 3 × 112
4.Which number has the prime factorisation 3 × 7 × 11?
Answer: 231
- 3 × 7 × 11 = 231
5.Use a factor tree to write 196 as a product of prime factors in index form.
Answer: 22×72
- 196 = 2 × 98
- 98 = 2 × 49
- 49 = 7 × 7
- So 196 = 2 × 2 × 7 × 7 = 22 × 72
6.Which number has the prime factorisation 7 × 112?
Answer: 847
- 7 × 11 × 11 = 847
7.Use a factor tree to write 140 as a product of prime factors in index form.
Answer: 22×5×7
- 140 = 2 × 70
- 70 = 2 × 35
- 35 = 5 × 7
- So 140 = 2 × 2 × 5 × 7 = 22 × 5 × 7
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.