Finding LCM and GCF Using Prime Factors

The video tutorial explains how to find the least common multiple (LCM) and greatest common factor (GCF) of the numbers 18 and 27 using factor trees. It demonstrates creating factor trees for both numbers, identifying prime factors, and using these to calculate the LCM and GCF. The tutorial concludes with a call to action to subscribe for more math and science videos.

What is the purpose of using a factor tree in this video?

• To find the sum of two numbers

• To identify the prime factors of numbers

• To calculate the average of numbers

• To determine the square root of numbers

Which of the following is a prime factor of 18?

• 2

• 5

• 6

• 4

What is the prime factorization of 27?

• 3 x 3 x 2

• 2 x 3 x 3

• 3 x 3 x 3

• 2 x 2 x 3

How do you determine the LCM using prime factors?

• Add all prime factors together

• Multiply all prime factors, using each pair only once

• Divide the largest prime factor by the smallest

• Subtract the smallest prime factor from the largest

What is the LCM of 18 and 27?

• 54

• 72

• 36

• 81

What is the definition of the Greatest Common Factor (GCF)?

• The smallest factor that divides two numbers

• The largest factor that divides two numbers

• The product of all factors of two numbers

• The sum of all factors of two numbers

Which vertical pair of prime factors is used to find the GCF of 18 and 27?

• 3 and 3

• 3 and 9

• 2 and 3

• 2 and 2

What is the GCF of 18 and 27?

• 3

• 6

• 9

• 12

Why can't the number 2 be used in finding the GCF of 18 and 27?

• It is not a vertical pair

• It is larger than both numbers

• It is not a factor of both numbers

• It is not a prime number

What does the video encourage viewers to do at the end?

• Subscribe and share the video

• Solve more math problems

• Watch another video

• Read a math book