GCF and LCM Challenges for 6th Graders

1. Sarah has 24 apples and 36 oranges. What is the greatest common factor (GCF) of the number of apples and oranges she has?

• 18

• 24

• 12

• 6

2. Tom is organizing his toy cars into groups. He has 18 red cars and 30 blue cars. What is the least common multiple (LCM) of the number of red and blue cars?

• 90

• 60

• 108

• 72

3. A gardener is planting flowers in rows. He can plant 15 tulips and 25 daisies. What is the GCF of the number of tulips and daisies he can plant in each row?

• 20

• 10

• 15

• 5

4. Two friends are making bracelets. One uses 12 beads and the other uses 16 beads. What is the LCM of the number of beads they are using?

• 40

• 32

• 36

• 48

5. A teacher has 40 pencils and 60 erasers. What is the GCF of the number of pencils and erasers she has?

• 20

• 30

• 50

• 10

6. Lisa is baking cookies. She can make 8 chocolate chip cookies and 12 oatmeal cookies. What is the LCM of the number of cookies she can make?

• 16

• 20

• 30

• 24

7. A music teacher has 28 recorders and 42 flutes. What is the GCF of the number of recorders and flutes?

• 28

• 7

• 14

• 21

8. Mark is arranging his baseball cards. He has 20 cards from Team A and 30 cards from Team B. What is the LCM of the number of cards from both teams?

• 40

• 30

• 60

• 50

9. A baker has 18 cupcakes and 24 cookies. What is the GCF of the number of cupcakes and cookies he has?

• 6

• 24

• 18

• 12

10. Two runners are training for a race. One runs every 15 days and the other every 20 days. What is the LCM of the days they run?

• 75

• 45

• 30

• 60