Transcript Adding and Subtracting Fractions with unlike Denominators

By Doug Harley
“I Can’t. I simply can’t.”

Fractions are not ready to be added until
they have a common denominator.
Response: My Left Side

“I can’t. I simply can’t. Those fractions
are not ready to be added.”
Response: My Right Side

“Stop!!! Back away from those fractions.
Those fractions are not ready to be
added.”
Objective
Without using any notes, you will be
able to add and subtract fractions with
unlike denominators with 90%
accuracy.
Least Common Denominator
(LCD)

Given the fractions 1/6 and 3/8, you
should be able to calculate that the LCD
is 24.
Building up Fractions
Given that the LCD for the fractions 1/6
and 3/8 is 24, you should be able to
build up each fraction to obtain an
equivalent fraction with the LCD.
 1/6 = 4/24
 3/8 = 9/24

Adding Fractions with like
Denominators
Given two fractions with like
denominators, you should be able to
calculate the sum of the two fractions.
 4/24 + 9/24 = 13/24

Subtracting Fractions with like
Denominators
Given two fractions with like
denominators, you should be able to
calculate the difference of the two
fractions.
 9/24 - 2/24 = 7/24

Simplifying Fractions
Given a fraction that can be reduce, you
should be able to reduce the fraction.
 12/15 = 4/5

Adding Fractions with unlike
Denominators
Given two fractions with unlike
denominators, you should be able to
calculate the sum of the two fractions.
 3/5 + 2/7 = 31/35

Resources

Waztamann, (2009). I simply can’t.
Retrieved from:
http://www.youtube.com/watch?v=Wu4o
noiOzQw&feature=related