Grade 4 · Math · Unit 3 of 16
Prime & Composite
Count factors to sort numbers into prime and composite
What your child practises
A prime number has exactly two factors, 1 and itself (like 7). A composite number has more than two (like 12). 1 is neither. Children find factors with multiplication and division facts.
Alberta Curriculum learning outcome: 4N3.1 · factors, and explaining prime and composite numbers using multiplication and division
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which number is composite?
- 3
- 9
- 17
- 19
Show answer
9
Hint: A composite number has more than two factors. 9 has factors 1, 3, 9.
Question 2
Which number is a factor of 20?
- 12
- 4
- 14
- 6
Show answer
4
Hint: A factor divides 20 with nothing left over. 4 × 5 = 20.
Question 3
What number goes in the box?
6 × = 36
answer box
Show answer
6
Hint: Think of the related division: 36 ÷ 6 = 6.
Question 4
Which statement is true?
- Every number greater than 1 is prime
- Every odd number is prime
- Every even number is prime
- Every even number greater than 2 is composite
Show answer
Every even number greater than 2 is composite
Hint: Even numbers greater than 2 have 1, 2 and themselves as factors, so they have more than two factors.
Question 5
How many factors does 31 have?
- 7
- 1
- 2
Show answer
2
Hint: List the factors in pairs: 1, 31.
Question 6
Is 33 prime or composite?
- neither prime nor composite
- prime
- composite
Show answer
composite
Hint: 33 has more than two factors (1, 3, 11, 33), so it is composite.