Year 7 Prime Factorisation (Factor Trees) Worksheet — Level 3 — 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 — 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 275 as a product of prime factors in index form.
Answer: 52×11
- 275 = 5 × 55
- 55 = 5 × 11
- So 275 = 5 × 5 × 11 = 52 × 11
2.Which number has the prime factorisation 2 × 32 × 5?
Answer: 90
- 2 × 3 × 3 × 5 = 90
3.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
4.Which number has the prime factorisation 22 × 5 × 11?
Answer: 220
- 2 × 2 × 5 × 11 = 220
5.Use a factor tree to write 375 as a product of prime factors in index form.
Answer: 3×53
- 375 = 3 × 125
- 125 = 5 × 25
- 25 = 5 × 5
- So 375 = 3 × 5 × 5 × 5 = 3 × 53
6.Which number has the prime factorisation 3 × 52 × 7?
Answer: 525
- 3 × 5 × 5 × 7 = 525
7.Use a factor tree to write 70 as a product of prime factors in index form.
Answer: 2×5×7
- 70 = 2 × 35
- 35 = 5 × 7
- So 70 = 2 × 5 × 7 = 2 × 5 × 7
8.Which number has the prime factorisation 2 × 33 × 5?
Answer: 270
- 2 × 3 × 3 × 3 × 5 = 270
Marking tips
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