Finding LCM and GCF with Factor Trees

This tutorial explains prime factorization, a method of breaking numbers into prime factors. It defines prime and composite numbers, using examples like 3 and 9. The video demonstrates the factor tree method for prime factorization, using numbers like 24 and 36. It also shows how to find the greatest common factor (GCF) and least common multiple (LCM) using factor trees, providing a step-by-step guide to these processes.

What is the definition of prime factorization?

• Breaking numbers into all composite numbers

• Breaking numbers into all prime numbers

• Breaking numbers into all odd numbers

• Breaking numbers into all even numbers

Which of the following is a prime number?

• 4

• 6

• 9

• 5

Tags

CCSS.4.OA.B.4

What is a composite number?

• A number that cannot be factored

• A number with only one factor

• A number with more than two factors

• A number with exactly two factors

Tags

CCSS.4.OA.B.4

In a factor tree, which number cannot be used?

• 5

• 2

• 3

• 1

Tags

CCSS.6.EE.A.1

What are the prime factors of 24?

• 2, 2, 2, 3

• 2, 3, 4

• 4, 6

• 1, 24

What are the prime factors of 36?

• 2, 2, 3, 3

• 3, 12

• 1, 36

• 6, 6

What is the greatest common factor (GCF) of 24 and 36?

• 8

• 18

• 6

• 12

What is the least common multiple (LCM) of 24 and 36?

• 72

• 48

• 60

• 84

What is the first step in finding the GCF using factor trees?

• Add all numbers together

• Find the prime factors of each number

• Divide the numbers by 2

• Multiply all numbers together

What should you do with the unmatched numbers when finding the LCM?

• Multiply them by the top number of the opposite factor tree

• Add them to the GCF

• Subtract them from the GCF

• Ignore them