Sir, everybody giving different logic, different conclusion and a different answer. It proves that question is not so simple OR easy. I am still looking for a convincing reply of the question. For the sake of those who have not read first, post I repeat the question for their convenience :
Let me clarify that 1st shopkeeper had adjusted loss of the 2nd shopkeeper by replacing the said fake note with an original one as soon as he brought it to his notice. So there are no ifs and buts. Now tell total loss of the 1st shopkeeper who had returned change of 800 to thee girl and paid real currency note of 1000 to coverup loss of 2nd shopkekeper.