Finding the Greatest Common Factor

This lesson covers finding the greatest common factor (GCF) of numbers, a crucial skill for reducing fractions. It reviews prime factorization and demonstrates finding the GCF through examples with numbers like 12, 8, 18, 21, 24, 32, and 40. The process involves identifying common prime factors and multiplying them. The lesson emphasizes the importance of practice in mastering this mathematical skill.

What is the greatest common factor?

• The sum of all common factors of a group of numbers.

• The largest number that divides evenly into each number in a group.

• The product of all prime factors of a group of numbers.

• The smallest number that divides evenly into each number in a group.

Why is finding the greatest common factor important?

• It helps in multiplying fractions.

• It helps in adding fractions.

• It helps in dividing fractions.

• It helps in reducing fractions efficiently.

What is the prime factorization of 12?

• 2 x 3 x 3

• 2 x 6

• 3 x 4

• 2 x 2 x 3

Which of the following is a prime number?

• 8

• 3

• 6

• 4

Tags

CCSS.4.OA.B.4

What is the greatest common factor between 12 and 8?

• 8

• 6

• 4

• 2

What is the prime factorization of 8?

• 2 x 2 x 2

• 2 x 4

• 2 x 2 x 3

• 2 x 3 x 3

Tags

CCSS.4.OA.B.4

What is the greatest common factor between 18 and 21?

• 9

• 6

• 3

• 2

What is the prime factorization of 21?

• 2 x 7

• 3 x 3

• 3 x 7

• 2 x 3

What is the greatest common factor among 24, 32, and 40?

• 8

• 6

• 4

• 2

What is the prime factorization of 40?

• 2 x 2 x 2 x 3

• 2 x 2 x 2 x 5

• 2 x 3 x 3 x 5

• 2 x 2 x 3 x 5