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Unit 1.4: Least Common Multiple and Greatest Common Factor

Least Common Multiple (LCM)

The lowest number that is divisible by a set of numbers. It is found by listing all of the prime factors of each number and then multiplying them together

Least Common Multiple

Find the LCM of 16 and 20

Start by listing all the prime factors of each number

16:                                                           20:

                         

16 = 2 ⋅ 2 ⋅ ⋅ 2                                          20 = 2 5

Because 16 and 20 share some common numbers, we only need to use the repeats once

It becomes 2 ⋅ 2 ⋅ ⋅ 2 5 = 80

The LCM {16, 20} = 80

 

Greatest Common Factor (GCF)

The highest number that a set of numbers is divisible by

Greatest Common Factor

Find the GCF of 30 and 65

Start by listing all the factors of the two numbers

30: (1, 30) (2, 15) (3, 10) (5, 6)

65: (1, 65) (5, 13)

Look for the highest number both have in common

in this case its 5 so the GCF {30, 65} is 5

 

 

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ESET1140: Intermediate Technical Algebra Copyright © 2024 by froenico. All Rights Reserved.