 # Chapter 3. Section 3.1 LCMGCF multiples  Multiples of 4  4,8,12,16,20…  Multiples of 10  10,20,30,40,50…  Multiples are larger than the original.

## Presentation on theme: "Chapter 3. Section 3.1 LCMGCF multiples  Multiples of 4  4,8,12,16,20…  Multiples of 10  10,20,30,40,50…  Multiples are larger than the original."— Presentation transcript:

Chapter 3

Section 3.1 LCMGCF

multiples  Multiples of 4  4,8,12,16,20…  Multiples of 10  10,20,30,40,50…  Multiples are larger than the original number

LCM  Least Common Multiple  Can be calculated for 2 or more numbers  Remember: Multiples are larger than the original number  LCM asks for the smallest multiple that the numbers in question have in common

Method 1 & 2  Method 1: List out the multiples  Ex: Find the LCM of 7 and 5  7, 14,21,28,35,42,49, 56, 63, 70, 77  5, 10,15,20,25,30,35,40, 45,50,55,60,65,70, 75  Ex2: Find the LCM of 8 and 12  24  Try it: Find the LCM of 8 & 18

Method 2  Prime Factorization  Prime Factor each number  Choose the largest amount of each number that they have in common  Multiply with the numbers each do not have in common  You have your LCM  EX: LCM of 120 and 36  120 = 2 3* 3*5  36 = 2 2 *3 2  LCM = 2 3* 3 2* 5 = 8*9*5=360  Ex2: LCM of 12 & 4  12 = 2 2 *3  4 = 2 2  LCM = 2 2 *3 = 4 * 3 = 12  Try it: Find the LCM of 12, 18, & 40

GCF  Greatest Common Factor  Factors are smaller!!!  GCF = Greatest of the factors that the numbers have in common

Method 1  List out the Factors of the numbers  Ex1: 18 & 20  18 = 1,2,3,6,9,18  20 = 1,2,4,5,10, 20  GCF = 2  Try it:  Find the GCF of 25 & 52

Method 2  Prime Factorization Method  Same as LCM prime factoring except select the smallest amount of each and ignore the numbers they do not have in common.  Ex: 16 & 20  16 = 2 4  20 = 2 2 *5  GCF = 2 2 = 4  Try it:  Find the GCF of 32,40,56  GCF = 8

U TRY IT  Find the LCM of :  3 & 9  3, 12, 18  Find the GCF of:  12 & 54  24 & 36 & 60  You go to the bulk section of your online grocery store to buy bulk dvd-R’s. The deal is that you must order 20, 50 or 100. What size packages should the store keep in their warehouse so they never have to open a package because of an order by some customer?  GCF  10

HW 3.1  1 – 56 eoo  Problems 57 – 64 all except 60 & 61  Evens: 2, 6, 12, 18, 20, 24, 24, 26, 38, 44, 48, 50, 54, 56  Try to do the easy ones in your head

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