Lesson 4: Explore properties of prime and composite numbers to 100 by using multiples. — Practice Questions

1. 1. Which statement best explains why the number 52 is a composite number?

   • A. It is an even number greater than 2.
   • B. The sum of its digits is 7.
   • C. It ends in the digit 2.
   • D. It is greater than 50.

2. 2. What is the smallest even composite number? ___

3. 3. The number 88 is an even number greater than 2. Is this number prime or composite?

   • A. Prime
   • B. Composite

4. 4. The number 46 is an even number, so it is a multiple of 2. Because it is greater than 2, it must be composite. What is its smallest prime factor? ___

5. 5. Which of the following numbers is the only even prime number?

   • A. 14
   • B. 4
   • C. 2
   • D. 10

6. 6. When using the Sieve of Eratosthenes, why is the number 57 crossed out from a list of numbers from 1 to 100?

   • A. Because it is a multiple of 2.
   • B. Because it is a multiple of 3.
   • C. Because it is a multiple of 5.
   • D. Because it is a prime number.

7. 7. In the Sieve of Eratosthenes, you circle the prime 2 and cross out its multiples. Then you circle 3. What is the first multiple of 3 you cross out that was not already eliminated? ___

8. 8. Which of the following numbers is the first to be crossed out when you are eliminating the multiples of 7 in the Sieve of Eratosthenes?

   • A. 14
   • B. 21
   • C. 35
   • D. 49

9. 9. Using the Sieve of Eratosthenes, the number 119 gets crossed out because it is a multiple of which prime number? ___

10. 10. After using the Sieve of Eratosthenes to cross out all multiples of 2, 3, and 5, what is the smallest number greater than 5 that remains on the list?

    • A. 6
    • B. 7
    • C. 9
    • D. 11