Least Common Multiple
-
Upload
tallulah-lynch -
Category
Documents
-
view
37 -
download
2
description
Transcript of Least Common Multiple
![Page 1: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/1.jpg)
Least Common Multiple
Algebra Seminar2012-2013
![Page 2: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/2.jpg)
What is LCM?
• LCM stands for Least Common Multiple• LCM is used to find a common denominator
for two fractions in order to compare them.• LCM is defined as: the smallest number
that both numbers are factors of.
• Lets watch a short video from www.unitedstreaming.com on LCM.
![Page 3: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/3.jpg)
![Page 4: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/4.jpg)
Finding the LCMLeast Common Multiple (LCM):
Method 1: Make a list of multiples
Ex: Find the LCM of 4 and 9
9: 9, 18, 27, 36, 45,
4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40 44
36 is the LCM of 4 and 9
![Page 5: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/5.jpg)
More Examples of LCMEx: Find the LCM of 10 and 12
10:12:
10, 20, 30, 40, 50, 60, 70, 80, 90, 10012, 24, 36, 48, 60, 72, 84, 96, 108
60 is the LCM of 10 and 12
Ex: Find the LCM of 6 and 8
6:8:
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 728, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88
24 is the LCM of 6 and 8
![Page 6: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/6.jpg)
Tips for finding the Least Common Multiple
1. Make a list of multiples for each number2. Look for the smallest number they have in common3. If you are looking for the LCM of more than two numbers make more lists. The LCM must be common to ALL of the numbers.
5 = 5, 10, 15, 20, 25, 30, 35 6 = 6, 12, 18, 24, 30, 36 10 = 10, 20 , 30, 40, 50 , 60
![Page 7: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/7.jpg)
Put the following fractions in order from greatest to least without using a calculator:
6
1,9
5,
12
7,3
2
Using the LCM to Put Fractions in Order
Without a calculator, we cannot change the fractions to decimals. We will have to use LCM.
![Page 8: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/8.jpg)
Step 1: Find the LCM of the denominators
Using the LCM to Put Fractions in Order
![Page 9: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/9.jpg)
3: 3, 6, 9, 12, 15, 18, 21, 24, 27
30, 33, 36, 39, 42 …
6: 6, 12, 18, 24, 30, 36, 42, 48…
LCM = 36
The LCM of 6, 12, 9, and 3 is….
12: 12, 24, 36, 48 …
9: 9, 18, 27, 36, 45 …
![Page 10: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/10.jpg)
Step 2: Write equivalent fractions.
36x 6
x 6 6 12
736x 3
x 3 21
9
536x 4
x 4 20 3
236x 12
x 1224
![Page 11: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/11.jpg)
Greatest to Least
Step 3: Compare the numerators
6
1
36 6
12
73621
9
53620
3
23624
![Page 12: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/12.jpg)
Put the Fractions in Order
Now try this one.
![Page 13: Least Common Multiple](https://reader035.fdocuments.us/reader035/viewer/2022081513/56812bcb550346895d90235d/html5/thumbnails/13.jpg)
The correct answer is:
Here are some more to try.