CBSE Class 10 Answered

hcf is the highest common factor. when you write the prime factors of given numbers, whatever comes out as common to all numbers is the hcf.

e.g.

 50=2*5*5

12=2*2*3

18=2+3*3

we see that 2 is common to all, hence 2 is the hcf.

Also remember that if you can't 'see' any factors common in the factorisation, it doesn't mean there's no hcf.

it's 1.

lcm is the least common multiple. A number which a multiple of all given numbers but of all such multiples it's the least.

 e.g.

15=3*5

25=5*5

24=3*2*2*2

(no common factors,

 so hcf =1)

so what you can do is first find the hcf( it's easier), then take the product of the facors and divide it by the hcf

So, here,

 lcm=(3*5)(5*5)(3*2*2*2)/1=15*25*24

 whatever the product, it's the answer.