Using the euclids division algorithm to …

(i) Here 225 > 135 we always divide greater number with smaller one.
Divide 225 by 135 we get 1 quotient and 90 as remainder so that

225= 135*1 + 90
Divide 135 by 90 we get 1 quotient and 45 as remainder so that

135= 90*1 + 45

Divide 90 by 45 we get 2 quotient and no remainder so we can write it as
90 = 2*45+ 0

As there are no remainder so deviser 45 is our HCF

(ii) 38220>196 we always divide greater number with smaller one.
Divide 38220 by 196 then we get quotient 195 and no remainder so we can write it as

38220 = 196 * 195 + 0

As there is no remainder so deviser 196 is our HCF

(iii) 867>255 we always divide greater number with smaller one.
divide 867 by 255 then we get quotient 3 and remainder is 102

so we can write it as
867 = 255 * 3 + 102

Divide 255 by 102 then we get quotient 2 and remainder is 51

So we can write it as
255 = 102 * 2 + 51

Divide 102 by 51 we get quotient 2 and no remainder
So we can write it as

102 = 51*2+ 0

As there is no remainder so deviser 51 is our answer

( Copied from- http://ncerthelp.blogspot.in/)