Understanding LCM through Factor Trees

This video tutorial explains how to find the least common multiple (LCM) of 15 and 20 using factor trees. It demonstrates creating factor trees for both numbers, organizing prime numbers in a chart to minimize errors, and calculating the LCM by multiplying the prime numbers. The video concludes with a call to action to subscribe for more math and science content.

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

• To identify the prime factors of a number

• To add numbers together

• To subtract numbers

• To divide numbers

Which prime numbers are factors of 15?

• 5 and 7

• 2 and 3

• 3 and 5

• 2 and 5

What is the first step in creating a factor tree for 20?

• Multiply 20 by 2

• Divide 20 by 3

• Divide 20 by 2

• Add 20 to 5

Which of the following is a prime factor of 20?

• 8

• 2

• 4

• 6

How do you determine the LCM using the prime factors?

• Divide the largest prime factor by the smallest

• Add all the prime factors

• Multiply the highest power of each prime factor

• Subtract the smallest prime factor

What is the LCM of 15 and 20?

• 75

• 30

• 45

• 60

Which rule is followed when multiplying prime numbers to find the LCM?

• Use all numbers twice

• Use each number once

• Use only vertical pairs

• Use the smallest number only