Fractions

Need To Know

Prime Factoring

Operations on Fractions

Simplify (Reduce)
Multiply
Divide
Add
Subtract

Vocabulary

Definitions:

Prime numbers – are numbers that can only
be factored by one and itself.
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Prime factoring - means to write a
number as a product of only prime numbers.

Prime Factoring

Prime factor 48

Prime factor 420

Reducing Fractions

Reduce 5/15  9/21

Reduce 279/310

Multiplication of Fractions

Simplify each expression

Recall fraction multiplication

Division of Fractions

Recall – Division of fractions is the same
as

Simplify:

end

1.3.B Add and Subtract Fractions

Need To Know

How to add/subt. fractions with same
denominator
Rename fractions
Find Least Common Denominator
How to add/subt. fractions with different
denominator

Add and Subtract Fractions

Recall the method to add fractions

Recall the method to subtract fractions

Renaming Fractions

Recall how to use the “fancy one” to
rename fractions.

Least Common Denominator

Definition –
The least common denominator (LCD) for a
set of denominators is the smallest multiple
that each denominator can divide into evenly.

Examples: Find the LCD

How to find the LCD

There are three ways to find LCD’s

Use intuition
Use a list of multiples
Use the prime factoring method

How to find the LCD

Listing multiples method
Example: Find the LCD of 12 and 18

How to find the LCD

Prime factor method
Example: Find the LCD of 60 and 42.

Steps to find LCD

1. Prime factor each
denominator

2. Create a product
using each factor
raised to the
highest exponent
that occurs in any
one factoring

Add and Subtract Fractions

Recall how to add fraction

How to + or – fraction

Find the LCD
Rename each fraction
(use the “fancy one”)
Add numerators
Reduce

Practice

How to + or – fraction
1. Find the LCD
2. Rename (use the “fancy one”)
3. Add numerators
4. Reduce

Simplify:

Simplify:

Practice

How to + or – fraction
1. Find the LCD
2. Rename (use the “fancy one”)
3. Add numerators
4. Reduce

Simplify:

Simplify:

end