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He is a very shrewd person; he does mental arithmetic faster than you would do with a calculator. You may forget how many cups of tea you had in a day, but not him, not even after a week. Pappu may be illiterate, but he is skillfull in running a business. He knows the golden rule in business: customer is king. That is because satisfied customers will return for business, form a long-lasting relationship, and remain loyal. He focuses his attention equally on every customer. For example, he participates in all the discussions and debate with his customers, perhaps even surprising them by knowing more on the subject matter than them. In conversations with his customers, he will jot down in his dairy, which he keeps near at hand, the account of his regular customers who deal with him on a credit basis.
Chris