Greatest Common Factor and Prime Factors

The video tutorial explains how to find the greatest common factor (GCF) of 12 and 15 using a factor tree method. It begins by breaking down the numbers into their prime factors: 12 is factored into 2, 2, and 3, while 15 is factored into 3 and 5. These factors are then placed in a chart to identify common factors. The GCF is determined by identifying the common prime factors, which in this case is 3. The tutorial also covers scenarios where no common factors exist, in which case the GCF is 1.

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

• Add the numbers together

• Break down the numbers into their prime factors

• Multiply the numbers

• Divide the numbers by 2

Which of the following is a prime factor of 12?

• 4

• 6

• 2

• 8

What are the prime factors of 15?

• 2 and 3

• 5 and 6

• 3 and 5

• 2 and 5

How do you determine the greatest common factor from the chart?

• Add all the numbers in the chart

• Look for the largest number in the chart

• Identify the common prime factors and multiply them

• Subtract the smallest number from the largest

What is the greatest common factor of 12 and 15?

• 1

• 5

• 2

• 3