Finding GCF and LCM Using Prime Factors

The video tutorial explains how to find the Least Common Multiple (LCM) and Greatest Common Factor (GCF) of the numbers 25 and 30 using factor trees. It begins with creating factor trees for both numbers, identifying their prime factors. The LCM is found by multiplying the prime numbers, considering vertical pairs, while the GCF is determined by identifying common vertical pairs. The video concludes with a call to action to subscribe for more educational content.

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

• To divide numbers

• To subtract numbers

• To add numbers together

• To identify the prime factors of numbers

What are the prime factors of 25?

• 5 and 3

• 5 and 5

• 3 and 5

• 2 and 5

Which prime numbers are used to create the factor tree for 30?

• 5, 6, and 7

• 3, 5, and 7

• 2, 3, and 5

• 2, 4, and 6

What is the first step in calculating the LCM using the prime number table?

• Identify vertical pairs

• Multiply all prime numbers

• Add all prime numbers

• Subtract all prime numbers

What is the LCM of 25 and 30?

• 200

• 150

• 250

• 100

Why is it important to identify vertical pairs when finding the LCM?

• To subtract numbers correctly

• To ensure all numbers are used

• To avoid using duplicate numbers

• To add numbers correctly

What is the rule for finding the GCF using prime factors?

• Multiply only vertical pairs

• Add all numbers

• Multiply all numbers

• Subtract all numbers

What is the GCF of 25 and 30?

• 20

• 10

• 5

• 15

Which number is a vertical pair in the prime factorization of both 25 and 30?

• 7

• 5

• 3

• 2

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