Find the common denominator

Which of these numbers could NOT be a common denominator for these two fractions?
2/4   and   3/8

• 32
• 12
• 8
• 24

Which of these numbers could NOT be a common denominator for these two fractions?
1/6   and   1/4

• 12
• 18
• 24
• 36

Which of these numbers could NOT be a common denominator for these three fractions?
1/3   and 2/5   and   3/10

• 15
• 30
• 60
• 90

What do you need to have when adding unlike fractions?

• common denominator
• common numerator
• common numerator and denominator

Is this a correct answer?

• Yes, the student correctly added.
• No, you cannot add unlike denominators
• No, 5 + 7 is not 12
• No, 2 + 3 is not 5

What is the least common denominator you could use to subtract 1/3 and 1/4?

• 3
• 4
• 24
• 12

What is the least common denominator of 1/7 and 3/6?

• 14
• 21
• 7
• 42

What would be the common denominator for adding 1/2 + 3/4?

• 6

• 4

• 9

• 2

What would be the common denominator for adding 3/9 + 4/6?

• 9

• 12

• 18

• 27

Which fraction renames 3/4 with a denominator of 12?

• 3/12

• 4/12

• 12/12

• 9/12