When shopkeepers want to lure customers into buying a particular product, they typically offer it at a discount. According to a new study to be published in the Journal of Marketing, they are【C1】______a trick A team of researchers, led by Akshay Rao of University of Minnesota, looked at consumers"【C2】______ to discounting. Shoppers, they found, much prefer getting something extra free to getting something cheaper. The main reason is that most people are【C3】______at fractions. Consumers often struggle to realise, 【C4】______, that a 50% increase in【C5】______is the same as a 33% discount in price. They【C6】______assume the former is better value. In an experiment, the researchers sold 73% more hand lotion when it was offered in a【C7】______pack than when it carried an equivalent discount. This numerical blind【C8】______remains even when the deal【C9】______favours the discounted product. In another experiment, this time on his undergraduates, Mr. Rao offered two deals on loose coffee beans: 33% extra free or 33%【C10】______the price. The discount is【C11】______ the better proposition, but the experiment shows the supposedly clever students viewed them as 【C12】______ . Marketing types can draw lessons【C13】______just pricing, says Mr. Rao. When advertising a new car"s efficiency, for example, it is more【C14】______ to talk about the number of extra miles per gallon it does,【C15】______the equivalent percentage fall in fuel【C16】______ . There may be lessons for officials who【C17】______prices too. Even well-educated shoppers are easily【C18】______ . Sending everyone back to school for maths seems out of the question. 【C19】______ more prominently displayed unit prices in shops and advertisements would be a great【C20】______.