# CLASS-8SOME IMPORTANT RULES & RELATION BETWEEN HCF & LCM

SOME IMPORTANT RULES & RELATION BETWEEN HCF & LCM

1) The product of two numbers is equal to the product of their HCF & LCM

HCF X LCM = First number X Second number

2) The HCF of two numbers cannot exceed either of the numbers.

3) The LCM of two numbers cannot be less than either of the numbers.

4) The HCF of two co-prime numbers = 1, and if the HCF of two numbers is 1, the two numbers are coprime.

5) The LCM of two co-prime numbers = the product of the two number.

Example.1) Product of two number is 1125 and their HCF is 25 then find the LCM

Answer) HCF of the two number X LCM of the two numbers =  Product of the two numbers

Product of two numbers

LCM of two numbers  =  ------------------------------

HCF of the numbers

1125

=  -------------

25

=       45                 (Ans.)

Example.2) Find the HCF & LCM of the numbers 12 & 25

Answer) 12 & 25 are co-prime numbers, so HCF =  1 & LCM                                                                                                                          =  12 X 25  =  300             (Ans.)