Do you know that electronic scales give less weight when buying groceries?

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Recently, I read news reports about the issue of decimal points on electronic scales – people manage to make easy money at your expense, without you even realizing it. Electronic scales are calibrated and legal. The trick lies in the step of entering the unit price, and the market cannot supervise this. If you ask the vendor to round down one decimal place in the unit price, the price difference will be immediately apparent. I did a search online and found that similar reports appeared as early as 2012; an excerpt is as follows: Investigation: Overcharging for groceries. Based on information provided by insiders, the numbers on the scale at a beef stall in a farmers’ market caught the reporters’ attention. The price per kilogram for beef tendon should have been 52 yuan; logically, it should be marked at 52, but in reality the cashier entered 0.52 on the scale. The staff at the stall said that, when converted, it’s 26 yuan per jin of beef tendon. 0.35 kilograms of beef tendon; the price shown on the scale is 0.19, which is 19 yuan. But according to the normal calculation, at 52 yuan per kilogram, 0.35 kilograms should cost 18.2 yuan; the cashier charged 0.8 yuan too much. How did 18.2 yuan turn into 19 yuan? The reporter bought some braised beef at this store, and the same problem arose again. The soy-marinated beef costs 78 yuan per kilogram; it’s being weighed right now, and the cashier entered 0.78 in the price field on the electronic scale. The reporter asked whether it would be possible to omit the decimal point and enter 78, using the unit price indicated on the electronic scale, but the clerk refused and insisted on entering 0.78. According to the normal calculation, at 78 yuan per kilogram, for 0.235 kilograms, the amount due should be 18.33 yuan. But the clerk charged 19 yuan, charging the reporter 0.67 yuan too much. Insider insight: “Price calculation based on reduced units” is the reason. So what exactly is the problem here? Where does that discrepancy of a few cents come from? The reporter also conducted some experiments in an attempt to uncover the secrets behind those few cents. At a pork sales stall, the reporter purchased some ribs. The vendor used a similar weighing method. The reporter raised doubts about this, and upon hearing that, the owner added another rib to the scale; when the weight read 0.5 kilograms, the price remained unchanged at 0.17 – only at that point was the price considered normal. During the interviews, when asked why the units are not shown as plain numbers but with a decimal point in front, many vendors said that this is just the way electronic scales work. Subsequently, the reporter operated the electronic scale themselves and found that the unit price of the goods was not such that only decimals could be used as stated by the vendor earlier, with no possibility of displaying whole numbers. According to people familiar with the matter, in the unit price input field and the price display window of these platform scales, only two digits after the decimal point are shown, with precision to the cent. In the price display window, if there is a third significant digit after the decimal point, it is simply discarded and the next digit is carried forward; for example, 0.182 becomes 0.19. If the integer part of the product’s price is entered as a decimal value, sellers can take advantage of this unwritten rule to earn a few extra cents on each transaction.