Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 4 — Answers
Answer sheet with worked solutions for the Year 5 factors, multiples & primes worksheet.
Success TutoringWorksheetsAnswer sheetYear 5 · Mathematics · Factors, Multiples & PrimesYear 5 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 100 as a product of prime factors in index form.
Answer: 22×52
- 100 = 2 × 50
- 50 = 2 × 25
- 25 = 5 × 5
- So 100 = 2 × 2 × 5 × 5 = 22 × 52
2.Which number has the prime factorisation 22 × 7 × 11?
Answer: 308
- 2 × 2 × 7 × 11 = 308
3.Use a factor tree to write 539 as a product of prime factors in index form.
Answer: 72×11
- 539 = 7 × 77
- 77 = 7 × 11
- So 539 = 7 × 7 × 11 = 72 × 11
4.Which number has the prime factorisation 22 × 3 × 7 × 11?
Answer: 924
- 2 × 2 × 3 × 7 × 11 = 924
5.Use a factor tree to write 980 as a product of prime factors in index form.
Answer: 22×5×72
- 980 = 2 × 490
- 490 = 2 × 245
- 245 = 5 × 49
- 49 = 7 × 7
- So 980 = 2 × 2 × 5 × 7 × 7 = 22 × 5 × 72
6.Which number has the prime factorisation 52 × 7?
Answer: 175
- 5 × 5 × 7 = 175
7.Use a factor tree to write 150 as a product of prime factors in index form.
Answer: 2×3×52
- 150 = 2 × 75
- 75 = 3 × 25
- 25 = 5 × 5
- So 150 = 2 × 3 × 5 × 5 = 2 × 3 × 52
8.Which number has the prime factorisation 22 × 32 × 11?
Answer: 396
- 2 × 2 × 3 × 3 × 11 = 396
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.