Printable Prime Factorization Worksheets
Printable prime factorization worksheets for 4th and 5th grade, with an answer key on every sheet. The sets below cover 5 different skills, so you can start where your child actually is. Available as visual guides and speed drills.
Targeted Practice by Skill
About Prime Factorization
What this skill is
Prime factorization breaks composite numbers down into a unique product of prime numbers (e.g., 24 = 2 x 2 x 2 x 3 = 2^3 x 3) using factor trees.
When children learn it
Prime factorization factor trees are taught in 4th and 5th grade.
Teaching Tips
- Circle prime numbers at branch ends until all branch ends are circled.
- Write final prime factors in ascending numerical order.
Common Mistakes
- Stopping factor tree branches before reaching prime numbers.
- Including 1 in prime factorization string lists.