7th Grade Prime Factorization (Factor Trees) Worksheet — Level 3 — Practice Set 2 — Answers
Answer sheet with worked solutions for the 7th Grade factors, multiples & primes worksheet.
Success TutoringWorksheetsAnswer sheet7th Grade · Mathematics · Factors, Multiples & Primes7th Grade Prime Factorization (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 756 as a product of prime factors in index form.
Answer: 22×33×7
- 756 = 2 × 378
- 378 = 2 × 189
- 189 = 3 × 63
- 63 = 3 × 21
- 21 = 3 × 7
- So 756 = 2 × 2 × 3 × 3 × 3 × 7 = 22 × 33 × 7
2.Which number has the prime factorization 2 × 32 × 72?
Answer: 882
- 2 × 3 × 3 × 7 × 7 = 882
3.Use a factor tree to write 605 as a product of prime factors in index form.
Answer: 5×112
- 605 = 5 × 121
- 121 = 11 × 11
- So 605 = 5 × 11 × 11 = 5 × 112
4.Which number has the prime factorization 52 × 7?
Answer: 175
- 5 × 5 × 7 = 175
5.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
6.Which number has the prime factorization 3 × 52?
Answer: 75
- 3 × 5 × 5 = 75
7.Use a factor tree to write 242 as a product of prime factors in index form.
Answer: 2×112
- 242 = 2 × 121
- 121 = 11 × 11
- So 242 = 2 × 11 × 11 = 2 × 112
8.Which number has the prime factorization 2 × 32 × 5 × 11?
Answer: 990
- 2 × 3 × 3 × 5 × 11 = 990
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.
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