1. Adding and Subtracting Fractions
Number Sense 1.2

2. How to add/subtract fractions.
In order to add/subtract fractions, the denominator must be the same. Example: ¼ + 2/4 = ¾ If the denominator is not the same, you must find the least common multiple of the denominators (This can also be called the Least Common Denominator).

3. Unlike Denominators: Step 1: Use the upside down cake method to determine the LCM Step 2: The LCM becomes the new denominator for each fraction.
3/8 + 1/6 =
[8 6]
4 3
2  4  3
LCM = 24 2

4. 3/8
1/6
Step 3: Determine what factor multiplies to make the LCM. Multiply the numerator by that factor. Step 4: Always simplify when possible
9/24
4/24
13/24

5. 2/3 + 1/5
Four Square Method: Write the steps in you own words. 1) 2) 3) 4) 2 2 10 3 15
Denominator 3
Answer: 13/15

6. Practice
Add.
Answers:
1.) 2/3 + 1/5 2.) 4/9 + 1/3 3.) 3/7 + 1/3 4.) 1/2 + 3/8 5.) 3/8 + 1/4
1.) 13/15 2.) 7/9 3.) 16/21 4.) 7/8 5.) 5/8