Understanding LCM and GCF

This video tutorial explains how to find the Lowest Common Multiple (LCM) and Greatest Common Factor (GCF) of the numbers 12, 15, and 21 using factor trees. The instructor demonstrates creating factor trees for each number, identifies the prime factors, and then calculates the LCM by multiplying the necessary prime factors. The GCF is determined by identifying the common prime factor among the numbers. The video concludes with a call to action to subscribe for more math and science content.

What does LCM stand for?

• Least Common Measure

• Largest Common Multiple

• Lowest Common Measure

• Lowest Common Multiple

What are the prime factors of 12?

• 2, 2, 3

• 3, 3, 2

• 2, 3, 5

• 2, 2, 5

Which of the following is a prime factorization of 15?

• 3 x 5

• 2 x 7

• 3 x 3

• 5 x 5

What are the prime factors of 21?

• 2, 3

• 2, 5

• 3, 5

• 3, 7

How do you calculate the LCM of multiple numbers?

• Multiply all prime factors, using common factors only once

• Add all prime factors together

• Multiply only the common prime factors

• Divide the largest number by the smallest

What is the LCM of 12, 15, and 21?

• 120

• 210

• 60

• 420

What does GCF stand for?

• Greatest Common Function

• Greatest Common Fraction

• Greatest Common Factor

• Greatest Common Formula

Which number is the GCF of 12, 15, and 21?

• 3

• 5

• 7

• 2

What is the largest number that divides 12, 15, and 21 evenly?

• 2

• 7

• 5

• 3

Which of the following is a method to find the GCF?

• Identify the common prime factor in all numbers

• Multiply all numbers together

• Divide the largest number by the smallest

• Add all numbers together