After retiring, Third Master Zhang had nothing to do. He often went for a stroll at his daughter Zhang Qian's vegetable store. When her daughter was too busy, she would help out. In this way, Third Master Zhang became a volunteer employee in his daughter's vegetable store.

Zhang Sanye has a strong sense of responsibility, welcomes customers with a smile, and is enthusiastic about service. In order to attract customers, he often gives his daughter ideas. The dishes sold in the vegetable shop are fresher and cheaper than those sold in other stores. As a result, the business of the vegetable shop is more and more prosperous, and the door is full of markets, returning customers day by day.

One day, Zhang Qian went to a relative's wedding and entrusted the vegetable shop to Third Master Zhang alone. There were more customers than ever that day, and Third Master Zhang was very busy. Zhang Qian came back from the banquet and started counting the money after closing. Suddenly, she held a hundred-yuan bill and was stunned. Third Master Zhang noticed that his daughter's eyes were wrong and asked, "What's the matter?" Zhang Qian touched the money repeatedly, then looked at the light again, and said uncertainly, "This money may be fake." "What? It's fake money? This damn liar, use fake money to deceive people, don't let me touch him again next time!" Saying that, Third Master Zhang took out a hundred yuan from his pocket and gave it to Zhang Qian. Zhang Qian didn't ask for it, but said with a smile, "Dad, don't worry. It's not certain if this money is real or fake. I just look like it. I'll take it to the bank for identification tomorrow."

The next day, Zhang Qian went to the bank and was identified by the bank staff as a fake.

When Third Master Zhang found out, he insisted on giving his daughter a hundred yuan to make up for the loss. How could Zhang Qian ask for it, so he smiled and comforted, "Dad, it's not a big deal, isn't it just a hundred yuan? In the future, when I'm not at home, I have to rely on you to take care of the store. Just pay more attention when you collect money in the future."

Not long after, one evening, there were many people came into the store to buy food. Zhang Qian herself also received a fake hundred yuan bill when collecting the money. She was very depressed and said to herself, "It's really hard to prevent a liar from using fake money to deceive people. Some fake money is really hard to identify.

Third Master Zhang knew that his daughter had received fake money and was very annoyed. He wanted to buy a money detector. The vegetable shop did not have this condition, and it would also increase the procedures for buying and selling vegetables.

Zhang Qian asked impatiently, "What solution?"

Third Master Zhang smiled and said, "I'm not completely sure yet, the secret cannot be revealed, but you have to do as I say."

"What am I doing? Dad, if you say it, I will do it." Zhang Qian said happily.

Third Master Zhang frowned and said, "You go buy a set of chess, and then buy a small square table and put it in the room of the vegetable store."

Zhang Qian asked doubtfully, "Why do you buy chess? I'm in the business of selling vegetables, not entertainment."

Seeing that Zhang Qian didn't believe it, Third Master Zhang urged, "Don't think about it, just do it quickly."

Zhang Qian was like the second monk of Zhang for a while, but he still did it according to the requirements of Third Master Zhang.

Soon, there was a group of old people playing chess in Zhang Qian's vegetable shop. Some of them were unfamiliar faces, and they seemed to be old acquaintances of Dad. Every day, everyone had tea made by Dad in front of them.

When Zhang Qian went out to buy goods, she handed over the vegetable shop to Third Master Zhang to take care of. In the blink of an eye, more than half a year passed, and during this period, she never received a single fake money. Zhang Qian was very puzzled, what trick did her father use? Or maybe the liar never came.

On this day, Zhang Qian said to Third Master Zhang, "Over the past six months, the vegetable shop has been very peaceful, and I haven't received a single fake money."

Third Master Zhang said, "When you were not here, a liar came, but you were exposed on the spot."

"Dad, how did you do it? You bought a money detector?Zhang Qian asked in surprise.

Third Master Zhang smiled and said, "I don't have that ability, and I don't have a money detector."

"Then how do you distinguish between true and false?" Zhang Qian asked doubtfully.

Third Master Zhang raised his hand and pointed to the inner room: "Those old friends are my money detectors, haha."

Zhang Qian asked doubtfully, "Aren't they just a group of old people who have nothing to do after eating?" Dad, what are you kidding?"

Third Master Zhang smiled and said, "How could you know the secret here? That white-haired old man, surnamed Zhou, is my former neighbor who has been retired for five years. Your uncle Zhou worked in a bank before he retired. No matter what denomination of the money, he can tell the truth with his hand. After he retired, he had no hobbies. In order to pass the time, he gathered a few old friends to play chess under the tree every day. When it 's raining or cold in winter, he cannot go out to play chess. It is very boring. Your uncle Zhou is the best money detector. I set up a chess table in the vegetable store and invited him to play chess, so I don't have to worry about rainy days or cold days. He also brought a lot of chess friends. Every day when the chess is scattered, the chess friends buy some dishes from the vegetable store to take home. Once I received a large amount of money, I was not sure for a while, so I asked your Uncle Zhou to distinguish between the real and the fake. Your Uncle Zhou is really sharp-eyed, even more powerful than the money detector. You can tell him in touch. It's a god, the liar has come a few times, hit the wall, and never dared to come again. "

When Zhang Qian heard it, she suddenly realized it and happily said, "Dad, your trick is awesome!"