Understanding Highest Common Factor (HCF)

The video tutorial explains how to find the highest common factor (HCF) using factor trees. It introduces the concept of prime numbers and demonstrates the process with examples involving pairs of numbers: 9 and 27, 24 and 36, and 54 and 18. The tutorial emphasizes identifying common prime factors and multiplying them to find the HCF.

What is the highest common factor (HCF)?

• The largest number that divides two numbers

• The sum of two numbers

• The smallest number that divides two numbers

• The difference between two numbers

Which of the following is a prime number?

• 9

• 6

• 7

• 4

What is the HCF of 9 and 27?

• 3

• 6

• 12

• 9

In the factor tree method, what do you do after finding all prime factors?

• Add them together

• Multiply the common prime factors

• Subtract them

• Divide them

What is the first step in finding the HCF of 24 and 36?

• Divide 24 by 36

• Create a factor tree for 24

• Subtract 36 from 24

• Add 24 and 36

Which prime number is a factor of both 24 and 36?

• 5

• 7

• 2

• 11

What is the HCF of 24 and 36?

• 6

• 8

• 10

• 12

What is the first step in finding the HCF of 54 and 18?

• Subtract 18 from 54

• Create a factor tree for 54

• Divide 54 by 18

• Add 54 and 18

Which of the following is a common prime factor of 54 and 18?

• 7

• 4

• 5

• 3

What is the HCF of 54 and 18?

• 30

• 24

• 18

• 12