Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 3 — Practice Set 3 — 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 3 — 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 231 as a product of prime factors in index form.
Answer: 3×7×11
- 231 = 3 × 77
- 77 = 7 × 11
- So 231 = 3 × 7 × 11 = 3 × 7 × 11
2.Which number has the prime factorisation 23 × 53?
Answer: 1000
- 2 × 2 × 2 × 5 × 5 × 5 = 1000
3.Use a factor tree to write 480 as a product of prime factors in index form.
Answer: 25×3×5
- 480 = 2 × 240
- 240 = 2 × 120
- 120 = 2 × 60
- 60 = 2 × 30
- 30 = 2 × 15
- 15 = 3 × 5
- So 480 = 2 × 2 × 2 × 2 × 2 × 3 × 5 = 25 × 3 × 5
4.Which number has the prime factorisation 32 × 52?
Answer: 225
- 3 × 3 × 5 × 5 = 225
5.Use a factor tree to write 495 as a product of prime factors in index form.
Answer: 32×5×11
- 495 = 3 × 165
- 165 = 3 × 55
- 55 = 5 × 11
- So 495 = 3 × 3 × 5 × 11 = 32 × 5 × 11
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 350 as a product of prime factors in index form.
Answer: 2×52×7
- 350 = 2 × 175
- 175 = 5 × 35
- 35 = 5 × 7
- So 350 = 2 × 5 × 5 × 7 = 2 × 52 × 7
8.Which number has the prime factorisation 3 × 7 × 11?
Answer: 231
- 3 × 7 × 11 = 231
Marking tips
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