1. Adding and Subtracting Fractions
With different denominators

2. Different Denominators
                                              
                                
Different Denominators
It's easy to add and subtract like fractions, or fractions with the same denominator.
You just add or subtract the numerators and keep the same denominator. For example,
                                              
the answer is

3. Least Common Denominator
The least common denominator (LCD) of two or more fractions is the smallest number that can be divided evenly by each of the fractions’
For example if you have 1 and 1 what is
the least common denominator?

4. Adding Fractions
You just add the numerators and keep the same denominator.

5. Subtracting Fractions
You just subtract the numerators and keep the same denominator.

6. Least Common Denominator
We need some way to determine which fraction is larger.
Suppose Marcia and Melissa have some left over pizza.

7. Least Common Denominator
We can compare using slices of pizza.
If each person had 12 slices we can see Marcia had 1/12 more slices than Melissa.

8. Steps in finding the LCD
Convert unlike fractions to equivalent like fractions.
Find the smallest number that can be divided by both denominators.
This will be the least common denominator.

9. Finding the LCD
To find the smallest number each denominator can be divided into start by doing the following:
, 8, 12, 16
, 12, 18, 24
The of 4 and 6 is 12.
can be divided into
can be divided into
LCD

10. Create New Fractions
Next divide the original denominator into the new denominator (12 divided by 4 = 3).
Next, multiply the product by the original numerator (3 x 3 = 9).
This results in your new fraction. 12
Multiply by original numerator
new fraction
Divide original denominator

11. Add the new fractions
= 11
your answer is

12. Turn in your answers within 10 minutes.
Practice
Find the LCD for each pair of fractions.
Remember the steps!!!
Turn in your answers within 10 minutes.

13. Practice Answers
Here are the answers to your problems.

14. Online Extra Practice
Try out these examples on the following online resources:
Least common multiplier
Least common denominator
Interactive Tutorial

15. Games are Cool Practice!
Check out this website to try you chance at some least common denominator games.
Race against the clock to test your skills.
Visit the following site to play the game!
Least common denominator game

16. You Did It!!! Give yourself a pat on the back. Keep up the good work.
Here’s a reward especially for you!
APPLAUSE!!!