Prime Factors and GCF/LCM Concepts

This video tutorial explains how to find the Least Common Multiple (LCM) and Greatest Common Factor (GCF) of the numbers 5, 15, and 20 using factor trees and a prime chart. The process begins with creating factor trees for each number, identifying prime factors, and then organizing these factors into a prime chart. The video demonstrates how to calculate the LCM by multiplying the highest power of each prime number and the GCF by identifying common prime factors. The tutorial concludes with a call to action to subscribe and share the content.

What is the purpose of using a factor tree in finding LCM and GCF?

• To add numbers together

• To break down numbers into their prime factors

• To simplify the numbers

• To multiply numbers directly

Which of the following is a prime factor of 15?

• 5

• 4

• 2

• 6

Why is it important to circle prime numbers in a factor tree?

• To identify them as factors

• To ignore them

• To multiply them

• To add them

What numbers are used to create the prime chart for 20?

• 5, 3

• 2, 3

• 2, 5

• 3, 4

When calculating the LCM, what should you do if you have pairs or triplets of the same number?

• Use only one of them

• Multiply them together

• Ignore them

• Use them all

What is the LCM of 5, 15, and 20?

• 45

• 30

• 60

• 75

What rule is used to find the GCF when you have three numbers?

• Use all numbers

• Use only triplets of the same number

• Use the largest number

• Use the smallest number

Which number is the only triplet in the prime chart for 5, 15, and 20?

• 2

• 10

• 3

• 5

What is the GCF of 5, 15, and 20?

• 15

• 20

• 10

• 5

What should you do if a number does not appear in all factor trees when finding the GCF?

• Multiply it

• Add it

• Ignore it

• Use it anyway