A group of 7 Sardars

There is this group of 7 Sardars who plan to go to Delhi to thank the President Dr. Zail Singh for his revolutionary policies, from which they have greatly benefited. Moreover, they are his old friends, and are longing to dine with the president. They agree that it would be appropriate to use a taxi. So they go to a taxi driver and ask him how much a ride would cost. The driver frets a little and tells them,"Sahab! If only four of you were to be there I would charge you just the meter rate, but then since seven of you would be there, you have to give me Rs. 10/- more." The Sardars agree and decide to take the taxi. The taxi driver takes them to Rashtrapati Bhavan. The meter shows Rs. 18/-, so the taxi driver says,"You have to pay me Rs. 28/-." Now, the Sardars have to share the cost among themselves and so they decide to divide the total (Rs. 28/-) by the number of people, i.e. 7. This is how they do the calculation to arrive at the answer: The driver (naturally) is exceedingly happy upon receiving Rs. 13/- from each of the Sardars. He thanks them profusely and the feeling of exultant happiness is writtern on his face as he leaves them and proceeds his way. Seeing this, the Sardars feel that they may have made a mistake. They decide to ask Zail Singh about it. After all, the fellow was the President of the nation! After all the initial formalities are completed, they ask Zail Singh to check their calculation of the taxi fare. Zail Singh ponders over the calculations and finally says, "See, I am not good at division. The process just boggles me but addition is something I am an expert at. Let us add all the amounts you guys gave to the taxi driver and check the result. This is how I do for those tax forms I get very often. The process is slow but is sure." The other sardars nod their heads (?) in appreciation. The President writes as shown below and also explains as he writes on: 13+13+13+13+13+13+13= 28 i.e. 3+3+3+3+3+3+ 3= 21 and 21+1+1+1+1+1+ 1+1=28 so this checks out. He then says, "Yes, it's correct. But I can also call my close friend and Finance man Manmohan Singh. It is always better that he rechecks it. After all, he is a Finance man, you know!" Manmohan Singh arrives, and when told of the problem, he replies that he doesn't think it is a bad deal but says, "No problem! I will verify it via mathematical computation. I'll verify it with multiplication. That is the best technique for this, you see!" While others watch in admiration, Manmohan Singh goes on to write as shown: This checks out as well.Then he says,
"This is really fine. There should be no problem, President Sahab. After all, it is correct in all the methods."
Peace reigns at the President's residence as the inhabitants and guests remain in quite contentedness while they reminisce about their astute abilities on solving a problem in a successful fashion