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One day, a little boy comes into a shop and says to the shop assistant (售货员), "I want to buy twelve exercise books of 6 cents (美分) each and nine pencils of 10 cents each. How much is that altogether (总共)?"

The shop assistant writes these numbers down on a piece of paper and thinks for a minute. Then she says, "1 dollar 62 cents." "If I give you ten dollars, how much money will I get back?" "You will get 8 dollars 38 cents forchange. Here you are. These are the things you want. "

"No, thank you. I don't want to buy anything." The boy looks at the piece of paper and says politely (礼貌地), "This is my math homework. Thank you very much. Can I take it away?"