Greatest Common Factor and Factors

In this video, Mr. J explains how to find the greatest common factor (GCF) between two numbers. He provides four examples: 10 and 15, 12 and 6, 20 and 10, and 9 and 21. For each pair, he lists all factors, identifies common factors, and determines the greatest one. The video emphasizes understanding factors and provides tips for listing them efficiently. Mr. J concludes by summarizing the process and encouraging practice.

What is the greatest common factor (GCF) of two numbers?

• The largest number that divides both numbers without a remainder.

• The smallest number that divides both numbers without a remainder.

• The sum of the two numbers.

• The product of the two numbers.

Which of the following is a factor of 10?

• 7

• 4

• 3

• 5

What is the GCF of 10 and 15?

• 1

• 2

• 5

• 10

Which pair of numbers are factors of 12?

• 6 and 7

• 8 and 9

• 2 and 5

• 3 and 4

What is the GCF of 12 and 6?

• 6

• 4

• 3

• 2

Which of the following is a factor of 20?

• 9

• 3

• 4

• 7

What is the GCF of 20 and 10?

• 15

• 10

• 5

• 2

Which of the following is a factor of 9?

• 2

• 3

• 5

• 7

What is the GCF of 9 and 21?

• 2

• 3

• 1

• 4

Which of the following pairs of numbers are factors of 21?

• 5 and 6

• 2 and 10

• 3 and 7

• 8 and 9