Finding GCF and LCM Using Prime Factorization

This video tutorial explains how to find the prime factors of a number using factor trees. It demonstrates the process with examples of the numbers 24 and 36, showing how to break them down into their prime components. The tutorial also covers how to determine the greatest common factor (GCF) and the least common multiple (LCM) of two numbers by comparing their prime factorizations. The video emphasizes the importance of writing prime factors in ascending order to simplify finding the GCF and LCM, especially for larger numbers.

What method is introduced in the video for finding prime factors?

• Subtraction method

• Multiplication method

• Factor trees

• Division method

Tags

CCSS.4.OA.C.5

What are the two numbers whose product is 24?

• 3 and 8

• 4 and 6

• 2 and 12

• 5 and 5

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CCSS.4.OA.B.4

What are the prime factors of 24?

• 2, 2, 3, 3

• 2, 2, 2, 3

• 3, 3, 2

• 2, 3, 4

What is the product of the prime factors of 36?

• 2 x 2 x 3

• 3 x 3 x 3

• 2 x 3 x 3

• 2 x 2 x 3 x 3

Why is it advisable to write prime factors in ascending order?

• To save time

• To find the GCF and LCM more easily

• To make the numbers look neat

• To avoid mistakes

What is the greatest common factor (GCF) of 24 and 36?

• 18

• 6

• 12

• 8

How do you find the GCF using prime factorizations?

• By adding the prime factors

• By multiplying all the prime factors

• By matching and multiplying only the common prime factors

• By subtracting the prime factors

What is the first step in finding the least common multiple (LCM) of 24 and 36?

• Adding the prime factors

• Multiplying all the prime factors

• Stretching the prime factorization of 36

• Ignoring the unmatched factors

What is the least common multiple (LCM) of 24 and 36?

• 48

• 84

• 60

• 72

How do you determine the LCM from the prime factorizations?

• By subtracting the prime factors

• By using all the prime factors, including unmatched ones

• By adding the prime factors

• By using only the common prime factors