Download (denominator). - elearningadulted

Welcome to IRSC’s
LIVE Virtual Lesson
on:
Adding and Subtracting
Fractions
with
Like and Unlike
Denominators
Instructor: Lara DiMartino
How to participate in this
session:
Raising your hand
What you will learn today:
1. How to add fractions with like (common)
denominators.
2. How to subtract fractions with like
(common) denominators.
3. How to add fractions with unlike
denominators.
4. How to subtract fractions with unlike
denominators.
5. How to reduce/simplify fractions.
Why learn these skills?
• Fractions were invented long before decimal
numbers as a way of showing portions less
than 1.
• They're used in baking, in building, in sewing,
in the stock market - they're everywhere!
So, we need to understand them.
Parts of a Fraction
Numerator
______________
Denominator
Vinculum
Also written this way:
Numerator/Denominator
Understanding the Parts
Numerator:
• The top number.
• It is the number of parts you have.
• It functions as the dividend when dividing.
Denominator:
• The bottom number.
• It is the total number of parts of the whole.
• It functions as the divisor of the numerator
when dividing.
Understanding Fractions
• The whole numbers are the multiples of 1.
(1, 2, 3, 4, 5, and so on…)
• The fractions are its parts: its halves, thirds,
fourths, fifths, and so on.
( 1/2, 1/3 , 1/4, 1/5, …)
1 written in fraction form
This is 1 whole pizza.
There are 8 individual slices (parts).
These parts goes in the numerator spot.
There are 8 slices that make up the (whole) pizza.
This whole goes in the denominator spot.
1 is equal to 8/8.
A fraction is a part of 1.
A fraction has a value that is less than 1.
Example: This pizza shows 3 parts (numerator)
left of the whole 4 pieces (denominator).
What are Like
Denominators?
Denominators that are the same.
They have the same value.
Example:
• 3/4 and 1/4 both have 4 as
denominators.
• So, they have “like” denominators also
known as “common denominators”.
What are Unlike
Denominators?
Denominators that are different.
Example:
2/6 and 2/12 have different
denominators.
They have “unlike denominators”.
Adding Fractions with Like
Denominators
Step 1: Add the numerators.
Step 2: Keep the original common denominator
for the answer.
2/8
+ 1/8_
3/8
Subtracting Fractions with
Like Denominators
Step 1: Subtract the numerators.
Step 2: Keep the original common denominator
for the answer.
8/10
- 1/10
7/10
Instructional Video
More on Like Denominators…
Adding Fractions with
Unlike Denominators
Step 1: Find a common denominator that both original
denominators can divide into evenly.
Step 2: Put in the new common denominator.
Step 3: Calculate the new numerators.
Step 4: Add the new numerators.
Step 5: Keep the new common denominator for the
answer.
Step 1: Find a Common
Denominator
Example: 3/4 + 1/8 =
1. First, list the multiples of each denominator.
4: { 4, 8, 12, 16…}
8: { 8, 16, 24…}
2. Then look for the smallest number, that they
have in common, that appears in each list.
(This number (8) has to be evenly divisible by
both original denominators (4 and 8).
Our new common denominator is : 8!!!!
Step 2: Put in the new
common denominator.
3/4 -> ? /8
+ 1/8 -> ?/ 8
Step 3: Calculate the new
numerator(s).
Example:
3/4
/8 8/4 = 2 THEN 2 X 3 = 6
+ 1/8
/8 (Keep the same)
6/8
+ 1/8
1. Divide the original denominator (4) into the
new one (8).
2. Take that quotient (2) and multiply it by the old
numerator (3) . That product (6) is the new
numerator.
Step 4: Add the New
Numerators
6/8
+ 1/8
7/?
Step 5: Use the new
common denominator.
6/8
+ 1/8
7/8
Subtracting Fractions with
Unlike Denominators
Use the same steps as when
adding, but of course,
subtract instead.
Example:
4/7
- 2/5
Step 1: Find a common
denominator.
7: { 7, 14, 21, 28, 35…}
5: { 5, 10, 15, 20, 25, 30, 35…}
Both original denominators (7 and 5) must be
able to divide evenly into the new common
denominator.
Step: 2 Put in the new
common denominator.
4/7 -> ? /35
- 2/5 -> ? /35
Step 3: Calculate the new
numerators.
4/7  ? /35
-2/5  ? /35
20/35
- 14/35
35/7= 5 then 5 X 4 =
35/5= 7 then 7 X 2 =
Step 4: Subtract the new
numerators.
20/35
- 14/35
6/?
Step 5: Use the new
common denominator.
20/35
- 14/35
6/35
Is Your Answer in
Simplest Terms?
If not, you need to simplify (reduce).
Example:
5/12
+ 1/12
6/12
This can be reduced!
Reducing continuedWhat number can divide evenly into
both 6 and 12?
Determine the (GCF)greatest common factor.
Factors of 6: {1, 2, 3, 6}
Factors of 12: { 1, 2, 3, 4, 6, 12}
6 can divide into both!
6_
6= 1
12
6= 2
½ is the answer in simplest terms!
Instructional Video
More on how to reduce!
Any Questions?
Type your questions in the chat
window please for whiteboard
practice.
Print your participant
window.
• Why? To email to your instructor as proof of
attendance. To get 1 hour of credit towards your
10 hours this week.
• How? Place your cursor and left click your
mouse on the participant window. On your
keyboard, hold down the SHIFT and PRINT
SCREEN keys. Then open a Word document and
paste (Ctrl + V). Last, attach your word
document to an email and send it to your
instructor.
Final Comments
• This session has been recorded for you to play
back and view at any time.
• If you have any questions regarding this topic at
a later time, don’t hesitate to contact your
instructor.
• Don’t forget to use the Smarthinking tutor
feature within your class site. A tutor is available
to you 24 hours a day.
Thank you for coming!
I hope you will take
advantage of our future
LIVE virtual lessons and
will attend some of those
sessions as well.
Have a great day!