Prime factors and perfect squares

Answer Key - Grade 6 Math Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Ari follows a map clue. Which of these numbers is prime?

   • 7
   • 8
   • 1
   • 9
2. 2.

   Esme is stuck on a riddle: only one of these numbers is prime. Which one is it?

   • 21
   • 10
   • 13
   • 1
3. 3.

   Jun finds a riddle in a book. Which number has just two factors, itself and one?

   • 27
   • 1
   • 17
   • 16
4. 4.

   Kira wants 12 as a product of primes. You can type 5 × 5 × 7 or 5^2 × 7. What should Kira write?

   2, 2, 3
5. 5.

   Milo builds a factor tree for 20. You can type 5 × 5 × 7 or 5^2 × 7. What is 20 as a product of primes?

   2, 2, 5
6. 6.

   Noah picks a card. Which one shows 28 as a product of primes?

   • 1 × 2 × 2 × 7
   • 4 × 7
   • 2 × 7
   • 2 × 2 × 7
7. 7.

   Pia picks a card. Which one shows 45 as a product of primes?

   • 5 × 9
   • 1 × 3 × 3 × 5
   • 3 × 3 × 5
   • 3 × 5
8. 8.

   Bo draws a factor tree for 70. It splits first into 5 and 14. Then 14 splits into 2 and 7. What is the missing prime?

9. 9.

   Esme starts a factor tree for 36 with 36 = 4 × 9. After finishing the tree, what is 36 as a product of primes?

   2, 2, 3, 3
10. 10.

    Zee is stuck on a riddle: only one of these numbers is a perfect square. Which one is it?

    • 36
    • 38
    • 42
    • 35