Finding the Greatest Common Factor

The video tutorial from MooMooMath and Science explains how to find the greatest common factors (GCF) using a layered cake method. It provides two examples: first, finding the GCF of 36 and 78, and second, finding the GCF of 12, 48, and 90. The process involves dividing the numbers by common factors, starting with the smallest prime numbers, and continuing until no further division is possible. The tutorial emphasizes understanding the concept of prime numbers and their role in determining the GCF.

What is the first step in finding the greatest common factor using the layered cake method?

• Start with the largest number

• Multiply the numbers together

• Find a small number that divides both numbers

• Subtract the smaller number from the larger one

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CCSS.4.NBT.B.6

CCSS.5.NBT.B.6

When dividing 36 and 78 by 2, what are the resulting numbers?

• 18 and 39

• 20 and 38

• 12 and 39

• 18 and 40

Which number is prime in the example of finding the greatest common factor for 36 and 78?

• 18

• 13

• 6

• 39

In the example with 12, 48, and 90, what is the first number used to divide all three numbers?

• 4

• 3

• 2

• 5

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CCSS.5.OA.B.3

After dividing 12, 48, and 90 by 2, what are the resulting numbers?

• 6, 24, and 45

• 5, 23, and 44

• 8, 26, and 47

• 7, 25, and 46

What is the greatest common factor for the numbers 12, 48, and 90?

• 4

• 6

• 8

• 10