1. Least Common Multiple LCM 2 Methods

2. Product
The answer to a multiplication problem.
6 X 6 = 36

3. What is the product?
7 X 8 = 56

4. Name the first six multiples of 6
The product of a whole number multiplied times any other whole number.
Name the first six multiples of 6
6, 12, 18, 24, 30, 36

5. Name the first six multiples of 5
5, 10, 15, 20, 25, 30

6. Common Multiple
A Common Multiple is a number that is a multiple of two numbers.
Here are common multiples for the numbers 4 and 10
4 = 4, 8, 12, 16, 20, 24
10 = 10, 20, 30, 40, 50,

7. Least Common Multiple
LCM -
Smallest
number that a set of given numbers divides
evenly into.
Least Common Multiple -
It is useful to know how to do this so you can find a common denominator when adding or subtracting fractions.
THERE ARE TWO WAYS TO FIND LCM

8. Least Common Multiple Method # 1
TO FIND THE LCM OF TWO NUMBERS
List the multiples of both numbers
Find the least multiple that
both numbers have in common.

9. Least Common Multiple Method # 1
Make a List of Multiples
Find the LCM of 10 and 12.
10: 10
, 20
, 30
, 40
, 50
, 60
, 70
, 80
, 90
, 100
...
12: 12
, 24
, 36
, 48
, 60
LCM = 60

10. Least Common Multiple Method # 1
Make a List of Multiples
Find the LCM of 32 and 40.
32: 32
, 64
, 96
, 128
, 160
, 192
, 224
, 256
...
40: 40
, 80
, 120
, 160
LCM = 160

11. What is the Least Common Multiple of 4 & 10
4 = 4, 8, 12, 16, 20, 24
10 = 10, 20, 30, 40, 50,

12. What is the Least Common Multiple of 6 & 8
6 = 6, 12, 18, 24, 30, 36
8 = 8, 16, 24, 32, 40, 48

13. What is the Least Common Multiple of 3 & 9
3 = 3, 6, 9, 12, 15, 21,
9 = 9, 18, 27, 36, 45, 54

14. Method #1 is easy to do!
Method #1 is a good method if both of your numbers are really small.
What if you have really large numbers? It might take too long to keep listing multiples until you find a common multiple.
SO HERE IS METHOD # 2

15. Least Common Multiple Method # 2
1) Write the prime factorization of each number.
Select all common factors ONCE.
3) Then select the remaining factors and multiply.

16. Least Common Multiple Method # 218 20 2 9 2 10 3 3 2 5
Select all common factors once.
Then select the remaining factors.

17. Least Common Multiple Method # 245 72 5 9 8 9 3 3 2 4 3 3 2 2
Select all common factors once.
Then select the remaining factors.

18. Least Common Multiple Method # 2
Find the LCM of 48 and 80. 2
Common
Factors
Once 2 2 2
Remaining
Factors

19. SO I GUESS YOU ARE WONDERING
Least Common Multiple Method # 2
SO I GUESS YOU ARE WONDERING
When Are We Ever Gonna Have To Use This?

20. Least Common Multiple Method # 2
What is the LCM used for?
The LCM is used to find common denominators
so that fractions may be easily compared, added,
or subtracted.

21. Least Common Multiple Method # 2
The GCF and LCM are used so regularly that
most people find them mentally.
GCF = 1
GCF = 5 1) 2)
LCM = 72
LCM = 60
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22. Least Common Multiple Method # 2
The GCF and LCM are used so regularly that
most people find them mentally.
GCF = 4
GCF = 4 1) 2)
LCM = 60
LCM = 24
copyright©amberpasillas2010

23. Least Common Multiple Method # 2
THE END
Take Out Your Study Guide!!!

24. #9 Multiples A number that is added to itself becomes a multiple.
3, 6, 9, 12, 15,
Multiples of 3 =
Multiples can go on infinitely forever.
The least common multiple (LCM) is the least common number that is a multiple of 2 numbers.
It is useful to know this for adding fractions.

25. LCM is 12 LCM Make a List Method # 1 4 = 4, 8, 12, 16, 20…
#10
TO FIND THE LCM OF 4 and 12:
1) List the multiples of both numbers
4 = 4, 8, 12, 16, 20…
12 = 12, 24, 36…
2) Find the least multiple that both numbers have in common.
LCM is 12
This method is useful if both numbers are small.

26. 18 20 2 9 2 10 3 3 2 5 #11 LCM Prime Factorization Method # 2
1) List the prime factorization to find the LCM. 18 20 2 9 2 10 3 3 2 5
2) Select all common factors once.
3) Select all remaining factors, and multiply.