Highest Common Factor Problems

This video tutorial explains how to find the Highest Common Factor (HCF) of numbers. It begins with a basic definition of HCF and demonstrates finding HCF using factors with examples like 20 and 28, and 12 and 18. The tutorial then introduces finding HCF using prime factors, providing examples with numbers like 28 and 42, and 132 and 420. The video concludes with a summary of the methods discussed.

What does HCF stand for?

• Highest Common Factor

• Highest Common Fraction

• Highest Common Formula

• Highest Common Function

What is the HCF of 20 and 28?

• 4

• 8

• 2

• 6

Which of the following is a factor of both 20 and 28?

• 5

• 10

• 7

• 4

What is the HCF of 12 and 18?

• 2

• 3

• 6

• 9

Which number is a common factor of both 12 and 18?

• 10

• 6

• 8

• 5

What are the prime factors of 12?

• 2, 2, 3

• 2, 3, 3

• 2, 2, 2

• 3, 3, 3

What is the HCF of 12 and 18 using prime factors?

• 3

• 2

• 4

• 6

What is the first step in finding the HCF using prime factors?

• Divide all numbers

• Multiply all numbers

• List all prime factors

• List all numbers

If a prime factor appears twice in both lists, what should you do?

• Include it thrice

• Include it once

• Ignore it

• Include it twice

What is the HCF of 20 and 28 using prime factors?

• 8

• 4

• 2

• 6