Understanding LCM and GCF

The video tutorial explains how to find the Lowest Common Multiple (LCM) and the Greatest Common Factor (GCF) of the numbers 15 and 60. It begins with an introduction to the concepts of LCM and GCF, followed by a demonstration of creating factor trees for the numbers 15 and 60. The tutorial then details the steps to calculate the LCM by multiplying the prime factors, ensuring each common factor is used only once. Similarly, it explains how to find the GCF by multiplying only the common prime factors. The video concludes with a summary and encourages viewers to subscribe for more math and science content.

What is the Lowest Common Multiple (LCM) of two numbers?

• The largest number that divides both numbers evenly

• The smallest number that both numbers multiply into evenly

• The sum of the two numbers

• The difference between the two numbers

Which of the following is a prime factor of 15?

• 2

• 3

• 4

• 6

What are the prime factors of 15?

• 2 and 5

• 5 and 6

• 3 and 5

• 2 and 3

Which of the following is a prime factor of 60?

• 9

• 2

• 8

• 7

What are the prime factors of 60?

• 2, 2, 2, and 5

• 2, 3, 5, and 7

• 2, 2, 3, and 5

• 3, 3, 5, and 7

How do you calculate the LCM using prime factors?

• Divide the largest prime factor by the smallest

• Subtract the smallest prime factor from the largest

• Multiply all prime factors, using each factor the maximum number of times it appears in any number

• Add all prime factors together

What is the LCM of 15 and 60?

• 60

• 45

• 30

• 15

How do you calculate the GCF using prime factors?

• Subtract the common prime factors

• Divide the common prime factors

• Multiply the common prime factors found in both numbers

• Add all common prime factors

What is the GCF of 15 and 60?

• 20

• 10

• 15

• 5