The practice of adding 9/10 to the price of gasoline, also known as “9/10 centering,” is a pricing strategy used by gasoline retailers in the United States. The purpose of this practice is to create the perception of lower prices to consumers while still allowing the retailer to maintain a profit margin.

The use of 9/10 centering dates back to the early 20th century, when gasoline prices were typically expressed in fractions rather than decimal points. For example, a price of 23 and 3/10 cents per gallon would be expressed as 23 3/10. This system was inconvenient for consumers, as it required mental calculations to determine the total cost of gasoline.

In order to simplify the process for consumers, gasoline retailers began rounding prices up to the nearest whole number and adding 9/10 to the end. For example, a price of 23 and 3/10 cents per gallon would be expressed as 23 9/10, or 23.9. This system made it easier for consumers to quickly determine the cost of gasoline, as they could simply read the price as a whole number followed by a fraction.

Over time, the practice of 9/10 centering has become widespread in the gasoline industry, and it is now a common pricing strategy used by retailers in the United States. While the practice has been criticized by some for creating confusion and potentially misleading consumers, it remains a widely used pricing method in the industry.

It is worth noting that the use of 9/10 centering is not universal, and some gasoline retailers do not use this pricing strategy. In addition, the practice is not limited to gasoline, as it is also used by some retailers in other industries to create the perception of lower prices to consumers.