Chapter 1
Integers
Exercise 1.4
Highest common factors
Question(9 & 10)
08 – 09 – 2026
Student Learning Objectives (SLO)
• • By the end of the lesson, students will be able to:
• Define the Highest Common Factor (HCF).
• Identify factors and common factors of two or
more numbers.
• Find common factors of two or more numbers.
• Calculate HCF using the listing method.
• Apply HCF to solve simple word problems.
Question 9.
Find the highest common factor of 54, 72 and 90.
Answer:
Factors of 54 are 1, 2, 3, 6, 9, 18, 27, 54.
Factors of 72 are 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72.
Factors of 90 are 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90.
Common factors of 54, 72 and 90 are 1, 2, 3, 6, 9, 18.
The highest common factor of 54, 72 and 90 is 18.
Question 10.
Two numbers have a highest common factor of 4. One of the
numbers is between 10 and 20. The other number is between 20
and 40.
a. What are the two numbers? Find all the possible answers.
Answer:
Possible numbers between 10 and 20 are 12 and 16.
Possible numbers between 20 and 40 are 24, 28, 32 and 36.
Now
Factors of 12 are 1, 2, 3, 4, 6 and 12
Factors of 16 are 1, 2, 4, 8 and 16
Factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24
Factors of 28 are 1, 2, 4, 7, 14 and 28
Factors of 32 are 1, 2, 4, 8, 16 and 32
Factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36
The possible two numbers are;
12 and 28, 12 and 32,
16 and 28, 16 and 36.
b. How can you be sure you have all the possible answers?
Answer:
Because, those are the only numbers divisible by 4 that are between
10 and 40.
Home Work
Work Book
Exercise 1.4
Questions (1,3,4 and 5)
Pages (14,15)
Instruction : To be done in the
work book.