Students fix three prime/composite errors — 2 called composite, 9 called prime, and 1 called prime. Part B has four fill-in-the-blank questions about composite numbers having more than two factors, divisibility by 2, and divisibility by 5. Part C has two short-answer questions about using the digit-sum rule for 45 and determining whether 37 is prime.
Correctly classifying 1, 2, and odd composites like 9 addresses the most persistent prime/composite misconceptions.
Style:
Factors and Multiples
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
2 is composite because it is even.
Rewrite: 2 is prime because its only factors are 1 and 2. It is the only even prime number.
2. Fix the sentence:
9 is prime because it is odd.
Rewrite: 9 is composite because 3 × 3 = 9, so it has factors other than 1 and itself.
3. Fix the sentence:
1 is a prime number because its only factor is itself.
Rewrite: 1 is neither prime nor composite because a prime number must have exactly two distinct factors.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A composite number has more than 2 factors.
2. A number is divisible by 2 if its last digit is even.
3. A number is divisible by 5 if it ends in 0 or 5.
4. The smallest prime number is 2.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Explain how you can quickly tell if 45 is divisible by 3.
Add the digits: 4 + 5 = 9. Since 9 is divisible by 3, the number 45 is also divisible by 3.
2. Is 37 prime or composite? How do you know?
37 is prime because no number other than 1 and 37 divides it evenly. It is not divisible by 2, 3, 4, 5, or 6.
Factors and Multiples
★ Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1) Fix the sentence:
2 is composite because it is even.
Rewrite: 2 is prime because its only factors are 1 and 2. It is the only even prime number.
2) Fix the sentence:
9 is prime because it is odd.
Rewrite: 9 is composite because 3 × 3 = 9, so it has factors other than 1 and itself.
3) Fix the sentence:
1 is a prime number because its only factor is itself.
Rewrite: 1 is neither prime nor composite because a prime number must have exactly two distinct factors.
★ Part B: Fill in the Blank
Write the missing word or number on each line.
1) A composite number has more than 2 factors.
2) A number is divisible by 2 if its last digit is even.
3) A number is divisible by 5 if it ends in 0 or 5.
4) The smallest prime number is 2.
★ Part C: Short Answer
Answer each question in one or two complete sentences.
1) Explain how you can quickly tell if 45 is divisible by 3.
Add the digits: 4 + 5 = 9. Since 9 is divisible by 3, the number 45 is also divisible by 3.
2) Is 37 prime or composite? How do you know?
37 is prime because no number other than 1 and 37 divides it evenly. It is not divisible by 2, 3, 4, 5, or 6.
Ready to Practice?
Complete each section carefully.
9 Questions
15-20 minutes
Auto-graded
Retry anytime
🏆
Questions Correct
0
Correct
0
Incorrect
0
Skipped
0:00
Time
0%
Score
Review Your Answers
See what you got right, missed, or skipped.