एक दुकानदार फलों को क्रय एवं विक्रय करते समय वजन में छेड़छाड़ करके 10% तक ठगता है। उसका कुल लाभ प्रतिशत में होगा :

While buying he takes 10% more goods than he pays for, and while selling he charges 10% more than the goods he gives. Each cheat multiplies his money by 1.1, so overall he gets 1.1 × 1.1 = 1.21 times his cost – a gain of 21%.