Greatest Common Factor and Prime Numbers

This video tutorial explains how to use prime factorization to find the greatest common factor (GCF) and least common multiple (LCM) of two whole numbers. It begins with an introduction to prime and composite numbers, followed by a demonstration of finding prime factorization using a factor tree. The video clarifies the difference between factors and multiples and provides examples of finding the GCF and LCM of numbers like 8, 30, 18, and 27 using prime factors and Venn diagrams.

What is a prime number?

• A number that is a multiple of 10

• A number with more than two factors

• A number with exactly two factors

• A number with only one factor

Which of the following is a composite number?

• 2

• 3

• 5

• 10

What is the prime factorization of 40?

• 5 x 8

• 2 x 10 x 2

• 2 x 5 x 4

• 2 x 2 x 2 x 5

What is the difference between factors and multiples?

• Factors are numbers you multiply to get another number, multiples are the result of multiplying a number by an integer.

• Factors are always larger than multiples.

• Factors are only prime numbers, multiples are composite.

• Factors and multiples are the same.

What is the GCF of 8 and 30?

• 8

• 4

• 6

• 2

What is the LCM of 8 and 30?

• 120

• 150

• 90

• 60

Which prime factors are shared between 8 and 30?

• 2 and 3

• 2 only

• 3 and 5

• None

What is the GCF of 18 and 27?

• 3

• 6

• 12

• 9

What is the LCM of 18 and 27?

• 54

• 36

• 81

• 72

Which prime factors are shared between 18 and 27?

• 2 and 3

• 3 only

• 3 and 5

• None