Finding Greatest Common Factors and Multiples

The video tutorial explains how to find the greatest common factor (GCF) of two numbers, 28 and 42. It begins by listing all the factors of each number. For 28, the factors are 1, 2, 4, 7, 14, and 28. For 42, the factors are 1, 2, 3, 6, 7, 14, and 42. The tutorial then identifies the greatest factor common to both numbers, which is 14, and concludes with this as the correct answer.

What is the first step in finding the greatest common factor of two numbers?

• List all the factors of each number.

• Add the numbers together.

• Multiply the numbers.

• Divide the larger number by the smaller number.

Which of the following is a factor of 28?

• 7

• 11

• 9

• 15

Which pair of numbers multiplies to give 42?

• 4 and 10

• 5 and 8

• 6 and 7

• 3 and 9

What is the greatest common factor of 28 and 42?

• 28

• 7

• 14

• 21

Why is it important to find the greatest common factor?

• To add numbers more easily.

• To simplify fractions.

• To multiply numbers faster.

• To find the average of numbers.