1. HIGHEST COMMON FACTOR
( HCF )

2. The Highest Common Factor of two or more numbers is the greatest of all their common factors.

3. Methods for finding HCF
1) Listing method
2) Prime Factorisation Method
3) Division Method

4. HCF by Listing Method
12 and 18
HCF of
Factors of 12 :
1 ,
2 ,
3 ,
4 ,
6 , 12
Factors of 18 :
1 ,
2 ,
3 ,
6 ,
9 , 18
1 ,
2 ,
3 , 6
Common Factors : 6
HCF of 12 and :

5. HCF by Prime Factorisation Method
12 and 18
HCF of 2 12 2 18 3 9 2 6 3 3 3 3 1 1 12
= 2 x 2 x 3 18
= 2 x 3 x 3
HCF of 12 and : 2 x 3
= 6

6. HCF by Division Method
HCF of
12 and 18
< 1 ) 12 18
HCF of 12 and : 6 12 2 6 ) 12 12