Greatest Common Factor

This video tutorial explains how to find the greatest common factor (GCF) of two numbers using two strategies: listing factors and prime factorization. The first method involves listing all factors of the numbers and identifying the largest common factor. The second method uses prime factorization to find common prime factors and multiply them to get the GCF. Both methods are demonstrated with the numbers 54 and 81, showing that the GCF is 27.

What is the greatest common factor (GCF) of two numbers?

• The sum of the two numbers

• The largest number that divides both numbers

• The smallest number that divides both numbers

• The difference between the two numbers

Which of the following is a factor of 54?

• 9

• 5

• 7

• 11

What is the largest factor that 54 and 81 share?

• 9

• 18

• 54

• 27

What is the prime factorization of 54?

• 2 x 3 x 3 x 3

• 2 x 3 x 9

• 2 x 2 x 3 x 3

• 3 x 3 x 3 x 3

How do you find the GCF using prime factorization?

• Add the prime factors of both numbers

• Subtract the prime factors of one number from the other

• Multiply the common prime factors

• Divide the larger number by the smaller number