a close-up of a car

Photo by Miss Shari

According to research published in the Journal of Economic Psychology, many of us are gas pump ninjas. Psychologists analyzed over a thousand self-pumped gas purchases at a convenience store in upstate New York. And they found that we love pumping gas to the nearest whole number. 

Almost 60% of purchase values ended in .00 (zero cents). Another 7% ended in .01, which may be due to not being able to stop the pump in time to hit double zeroes:

chart, bar chart

Data via Journal of Economic Psychology

If we’re truly pumping gas in a random fashion, we would expect the frequency for each cent value to be 1%– yet there’s a very strong affinity towards .00. This trend held regardless of whether customers paid in cash or in credit (though cash customers had a greater tendency to pay in round numbers). 

Do these results apply to dollar values as well? Over 50% of purchase values had dollar amounts ending in 0 or 5:

chart, bar chart

Data via Journal of Economic Psychology

What gives? Psychologist Michael Lynn explains:

“The frequency of round numbers and the ease of processing them contribute to a preference for round numbers that may simply generalize to round prices.”

Whatever the reason, there’s something oddly satisfying about stopping the pump on a round number.

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