is it compulsory????

yes it is, as u don't known wat examiner want so u should not give him the chance to cut ur marks for that....

so it is complusory....
but not everywhere but at last when u calulate the final amount everytime..

Follow the trend in the question paper if in the question paper rupee symbol is not there then u need not put that if its there then put that rupee symbol in answer too.

This is my suggestion.

i think putting that symbol will help to make a good impression abt our awareness....