1. Adding & Subtracting Fractions
How to make equivalent fractions

2. Can we add 3/4 + 1/6? NO!!!
Why not?
Because we can only add & subtract like fractions!
What do we do now?
Make them into equivalent fractions
How?
Find the LCD- Least Common Denominator

3. Least Common Denominator
The LCD is the smallest number that can be divided by both denominators!

4. How do we find the LCD?
1. Find all multiples for both denominators 4 & 6
The lowest multiple that both 4 & 6 share is the LCD

5. Solving this is easy!
Caterpillar method !!!

6. LCD is 12!!! Caterpillar Method Find lowest number that matches 12 8 416 4 20
LCD is 12!!!
4*3
4*2
1*4
4*4
4*5 12 18 6 24 6
6*1
6*2
6*3
6*4

7. Multiply both sides of the fraction by 3 & 2.
Since 4x3=12 and 6x2=12 (12 is LCD!)

8. Now add across!
Remember to keep the denominator the same!

9. Congratulations! Remember…
1) Does this fraction have unlike denominators?
2) Yes? Then find LCD.
3) Find the LCD by finding lowest common multiple.

10. Cont…
4) Multiply both sides of the fraction with the multiples of the LCD.
5) Add the numerators and keep the same denominator!

11. Resources
Watch a girl add fractions! See