LCM and GCF Challenges for 6th Graders

1. Sarah has 12 apples and 18 oranges. What is the greatest common factor (GCF) of the number of apples and oranges she has?

• 6

• 3

• 12

• 9

2. A gardener is planting flowers in rows. If he can plant 8 flowers in each row and has 32 flowers, how many rows can he plant? What is the least common multiple (LCM) of the number of flowers per row and total flowers?

• 5 rows, LCM is 40

• 2 rows, LCM is 16

• 4 rows, LCM is 32

• 3 rows, LCM is 24

3. Two friends are making bracelets. One uses 15 beads and the other uses 25 beads. What is the GCF of the number of beads they are using?

• 5

• 20

• 10

• 15

4. A school is organizing a field trip for 48 students and 60 students. What is the LCM of the two groups to find out how many buses are needed if each bus can hold 12 students?

• 15

• 30

• 20

• 24

5. Emily and Jake are collecting stickers. Emily has 24 stickers and Jake has 36 stickers. What is the GCF of their stickers?

• 6

• 18

• 12

• 30

6. A factory produces 20 toys every hour and 30 toys every hour in another section. What is the LCM of the toys produced in both sections in one hour?

• 60

• 50

• 40

• 30

7. A baker is making cupcakes. If he can bake 18 cupcakes in one batch and 24 in another, what is the GCF of the batches he can make?

• 12

• 9

• 3

• 6

8. Two cyclists are riding at different speeds. One cycles every 15 minutes and the other every 20 minutes. How often will they meet at the starting point? What is the LCM of their cycling times?

• 75 minutes

• 60 minutes

• 45 minutes

• 30 minutes

9. A music teacher has 28 music sheets and 42 practice sheets. What is the GCF of the sheets to find out how many groups of sheets he can make?

• 21

• 7

• 14

• 28

10. A group of friends is planning a picnic. They want to arrange their sandwiches in groups of 10 and 15. What is the LCM of the group sizes to find out how many sandwiches they need to prepare?

• 30

• 25

• 35

• 20