Year 5 Prime Factorisation (Factor Trees) Worksheet — Level 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 — 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 154 as a product of prime factors in index form.
Answer: 2×7×11
- 154 = 2 × 77
- 77 = 7 × 11
- So 154 = 2 × 7 × 11 = 2 × 7 × 11
2.Which number has the prime factorisation 22 × 3 × 7 × 11?
Answer: 924
- 2 × 2 × 3 × 7 × 11 = 924
3.Use a factor tree to write 352 as a product of prime factors in index form.
Answer: 25×11
- 352 = 2 × 176
- 176 = 2 × 88
- 88 = 2 × 44
- 44 = 2 × 22
- 22 = 2 × 11
- So 352 = 2 × 2 × 2 × 2 × 2 × 11 = 25 × 11
4.Which number has the prime factorisation 52 × 7?
Answer: 175
- 5 × 5 × 7 = 175
5.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
6.Which number has the prime factorisation 2 × 3 × 5 × 7?
Answer: 210
- 2 × 3 × 5 × 7 = 210
7.Use a factor tree to write 990 as a product of prime factors in index form.
Answer: 2×32×5×11
- 990 = 2 × 495
- 495 = 3 × 165
- 165 = 3 × 55
- 55 = 5 × 11
- So 990 = 2 × 3 × 3 × 5 × 11 = 2 × 32 × 5 × 11
8.Which number has the prime factorisation 3 × 52 × 7?
Answer: 525
- 3 × 5 × 5 × 7 = 525
Marking tips
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