Printable Prime and Composite Numbers Worksheets
Printable prime and composite numbers worksheets for 4th grade, with an answer key on every sheet. The sets below cover 3 different skills, so you can start where your child actually is. Available as visual guides, speed drills, and word problems.
Targeted Practice by Skill
About Prime and Composite Numbers
What this skill is
Prime numbers have exactly two factors (1 and itself, e.g., 2, 3, 5, 7, 11). Composite numbers have more than two factors (e.g., 4, 6, 8, 9). Note: 0 and 1 are neither.
When children learn it
Prime and composite numbers are taught in 4th and 5th grade, aligned to 4.OA.B.4.
Teaching Tips
- Count total factors: exactly 2 factors = Prime; 3+ factors = Composite.
- Remember that 2 is the only even prime number.
Common Mistakes
- Thinking 1 is a prime number (it has only 1 factor, not 2).
- Assuming all odd numbers are prime (9, 15, 21 are composite).