---COMMON FACTORS---
Common factors are those numbers which are factors of all the given numbers.
12 factors are 1, 2, 3, 4, 6, 12
18 factors are  1, 2, 3, 6, 9, 18
Common factors of 12 and 18 are 1, 2, 3 and 6.

---Highest Common Factor (HCF)---
The Highest Common Factor (HCF) of two or more given numbers is the highest (or
greatest) of their common factors. It is also called as Greatest Common Divisor (GCD)
From the above table we found that common factors of 12 and 18 are 1, 2, 3 and 6.
What is the highest of these common factors? It is 6. So we can say that the Highest
Common Factor (HCF) of 12 and 18 is 6.

---Method of finding HCF---
1. Prime Factorisation Method
2. HCF by Continued Division Method


---1. Prime Factorisation Method---
The HCF of 12, 30 and 36 can also be found by prime factorisation as follows:
***Text book pg=37  i think to make that in good pic **

Find the HCF of 12, 16 and 28?

---2. HCF by Continued Division Method---
Divide the larger number by the smaller and then divide the previous divisor by the remainder until
the remainder is 0. The last divisor is the HCF of the numbers
Find the HCF of 56 and 64
***Text book pg 38 pic***
What is the HCF of any two
 (i) Consecutive numbers? (ii) Consecutive even numbers?
 (iii) Consecutive odd numbers?
What do you observe? Discuss with your friend

 Find the largest number which is a factor of each of the numbers 504, 792 and 1080?

 Find the HCF of the following numbers by prime factorisation and continued division
method?
i. 18, 27, 36 ii. 106, 159, 265
iii. 10, 35, 40 iv. 32, 64, 96, 128