Finding LCM and GCF Concepts

This video tutorial from MooMooMath and Science explains how to find the greatest common factor (GCF) and the lowest common multiple (LCM) of the numbers 45, 60, and 75 using factor trees. The instructor demonstrates creating factor trees for each number, organizing the prime factors in a chart, and then using these to calculate the GCF and LCM. The GCF is found by identifying common prime factors across all numbers, while the LCM is calculated by multiplying all prime factors, considering triplets only once. The video concludes with a summary of the results: GCF is 15 and LCM is 900.

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

• To simplify the numbers

• To find the prime factors

• To divide the numbers

• To add the numbers

Which of the following is a prime factor of 45?

• 10

• 4

• 2

• 5

What is the first step in creating a factor tree for 60?

• Divide by 3

• Divide by 2

• Divide by 10

• Divide by 5

How do you organize the prime factors in the chart?

• By writing them in descending order

• By writing them randomly

• By writing them in ascending order

• By writing similar numbers underneath each other

What is the greatest common factor (GCF) of 45, 60, and 75?

• 20

• 15

• 10

• 5

What rule is used for triplets when calculating the LCM?

• Bring down all numbers

• Bring down two numbers

• Ignore the triplet

• Bring down one number

What is the lowest common multiple (LCM) of 45, 60, and 75?

• 750

• 900

• 600

• 450

Which number is not a part of the triplet in the LCM calculation?

• 2

• 3

• None

• 5

What is the final step in calculating the LCM?

• Divide the numbers

• Multiply all the numbers together

• Subtract the numbers

• Add all the numbers

What is the key takeaway from the video?

• Kindness multiplies kindness

• Math is difficult

• Always use a calculator

• Numbers are confusing