Adding/Subtracting Fractions

• Math
• 4th Grade

Fraction Fun

Adding and Subtracting Unlike Denominators

Learning Objective: 

• Understand how to add and subtract fractions with unlike denominators
• Learn to find common denominators 

What do we already know about fractions?

Understanding Fractions

Fractions are numbers that represent part of a whole number. The top number is the numerator, and the bottom number is the denominator.

If you had 1/4 of a pizza and I want to add 1/2 of another pizza, how do we combine them?

Unlike Denominators

To add or subtract fractions with unlike denominators, find a common denominator first.

Finding Common Denominators

List multiples of each denominator to find the least common multiple (LCM) for both fractions

What are multiples of 1/4 and 1/2 

1/4

1/2

4

8

12

2

4

6

8

Lets 

Practice 

Adding

What is 1/3 + 1/6

1. 1/2
2. 2/9
3. 1/9
4. 2/3

What is 1/8 + 1/4?

1. 2/12
2. 3/8
3. 2/8
4. 3/4

Now 

lets try 

Subtracting

What is 4/5 - 1/2?

1. 2/5
2. 3/5
3. 3/10
4. 2/10

What is 5/6 - 2/3

1. 3/3
2. 1/3
3. 3/6
4. 1/6

Review and Summary

We learned to add and subtract 

fractions with unlike denominators. 

And remember practice makes perfect

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