HCF- HIGHEST COMMON FACTOR

THE HIGHEST COMMON FACTOR OF TWO OR MORE NUMBER IS THE HIGHEST NUMBER WHICH CAN DIVIDE THOSE NUMBERS EXACTLY 

In this topic we should remember the concept of Divisibility

Example 1 : HCF of  10 and 15 

Usually we find out all the factor of 10 and 15 but now here we observe highest number which is divisible both 10 and 15. 

          5   | 10   15 

               |_________

               |  2    3  

               Highest common factor means HCF of 10 and 15 is 5 

Example 2 : HCF of  18  and 45   

Both the numbers are divisible by 9 because sum of digit is 9 

          9   | 18   45 

               |_________

               |  2    5 

Highest common factor means HCF of 18 and 45 is 9

Example 3 : HCF of  72 and 84  

Both the numbers are divisible by 3 because sum of digit is 9 and 3

      3       | 84   72       

               |_________

      4       |  28   24          Both the numbers are divisible by 4     

               |_________

                   7     6

Highest common factor means HCF of 84 and 72 is 3*4=12. 

 Practice: write down the HCF of the following numbers

1. 35,42
2. 33,88
3. 64,80
4. 18,30
5. 75,125