Finding Common Denominators Worksheet
Part 1: Multiple Choice Questions
Choose the correct answer from the options given.

Which of the following is a common denominator for 2/5 and 3/4?
 a) 20
 b) 12
 c) 8
 d) 15

What is the common denominator for 1/3 and 2/7?
 a) 21
 b) 10
 c) 9
 d) 7

Which of the following is the smallest common denominator for 1/2 and 2/3?
 a) 3
 b) 4
 c) 6
 d) 12

What is the common denominator for 1/4 and 3/5?
 a) 20
 b) 10
 c) 15
 d) 12

Which of the following is a common denominator for 1/6 and 5/7?
 a) 42
 b) 30
 c) 21
 d) 12

What is the common denominator for 2/3 and 3/4?
 a) 12
 b) 8
 c) 6
 d) 24

Which of the following is a common denominator for 1/3 and 2/5?
 a) 15
 b) 8
 c) 10
 d) 12

What is the common denominator for 1/2 and 3/4?
 a) 8
 b) 4
 c) 6
 d) 12

Which of the following is a common denominator for 1/5 and 2/3?
 a) 15
 b) 10
 c) 5
 d) 6

What is the common denominator for 1/3 and 4/7?
 a) 21
 b) 10
 c) 9
 d) 7
Part 2: True or False
Indicate whether the statement is true or false.
Statement  True or False 

A common denominator is a multiple of the denominators of two or more fractions.  
To find a common denominator, you need to find the least common multiple of the denominators.  
When adding or subtracting fractions, you need to have the same denominator.  
You can always find a common denominator for any two fractions.  
When finding a common denominator, you only need to consider the denominators of the fractions. 
Part 3: Fill in the Blanks
Fill in the blanks with the correct word or phrase.
 To add or subtract fractions, you need to find a ____ denominator.
 A common denominator is a multiple of the ____ of the fractions’ denominators.
 The least common multiple is also known as the ____ common multiple.
 To find the least common multiple, you need to list the ____ of each number and find their common factors.
 When adding or subtracting fractions, you need to have the same ____.
Part 4: Problem Solving
Solve the following problems.
 Rachel has 2/5 of a pizza left, and John has 3/4 of a pizza left. What is the smallest amount of pizza they can have if they want to split it evenly?
 If 3/4 of a class are boys and 5/6 of the boys have brown hair, what fraction of the class are boys with brown hair?
 A recipe calls for 1/2 cup of sugar and 3/4 cup of flour. What is the smallest amount of each ingredient you can measure out if you want to make 3 batches of the recipe?
 If a tank can hold 3/5 of a gallon of water and another tank can hold 1/2 of a gallon of water, what is the smallest amount of water you can measure out if you want to fill both tanks equally?
 A group of friends order 2/3 of a large pizza and 1/4 of a small pizza. What is the smallest amount of pizza they can have if they want to split it evenly?
Part 5: Essay Questions
Answer the following essay questions in complete sentences.
 What is a common denominator? How do you find a common denominator for two or more fractions?
 Why is it important to have a common denominator when adding or subtracting fractions? What happens if you don’t have a common denominator?
 Can you always find a common denominator for any two fractions? Why or why not? What is the easiest way to find a common denominator?
 What is the least common multiple? How do you find the least common multiple of two or more numbers?
 Give an example of a reallife situation where you might need to find a common denominator. How would you solve the problem?