Math Worksheet · Grades 4–6
Prime and Composite Numbers Worksheet
A printable math worksheet for grades 4-6 on prime and composite numbers: a prime number has exactly two factors while a composite number has more than two. Students classify eight numbers, then answer four short questions including why 1 is neither. A complete answer key is included.
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Subject
Math
Grades
Grades 4–6
Skill Focus
Prime and Composite Numbers, place value
Lesson Length
20 minutes
Lesson Overview
About this worksheet
A factor divides into a number evenly, and we sort numbers by how many factors they have. A prime number has exactly two factors – 1 and itself; a composite number has more than two. The number 1 is special: it has only one factor, so it is neither prime nor composite. This worksheet teaches students to test a number by hunting for factors.
Section A lists eight numbers (5, 9, 11, 15, and others) and asks students to label each prime or composite, balanced four and four. The reference box teaches the rule with 7 (prime) and 8 (composite) examples and the find-a-factor test but does not reuse the Section A numbers.
Section B is short-answer. Students contrast prime and composite, list the factors of 12, explain why 1 is neither, and test whether 19 is prime. Page 3 is a complete answer key. The skill underpins factoring, fractions, and number theory.
How to Use This Lesson
Read the reference box aloud and find all the factors of 8 together to show it is composite.
Complete Section A independently – have students try to find a factor other than 1 and the number.
Work Section B item 3 together: 1 has only one factor, so it is neither prime nor composite.
Use the answer key on page 3 for self-check or teacher review.
Pair with the Factors and Multiples Worksheet or the Division Facts Worksheet for a number-theory mini-unit.
Printable Resource
A classroom-ready PDF with everything in one printable resource.
Full Member Resource · Printable PDF · 3 pages · Answer Key
Prime and Composite Numbers Worksheet
A printable math worksheet for grades 4-6 on prime and composite numbers: a prime number has exactly two factors while a composite number has more than two. Students classify eight numbers, then answer four short questions including why 1 is neither. A complete answer key is included.
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