If one is the loneliest number, then four is the hottest — at least when it comes to gasoline.

With regular gas in New York City at a near-record $4.40 a gallon, station managers are rummaging through their storage closets in search of extra 4s to display on their pumps. Many are coming up short.

That’s why Vishal Nair, who runs the Lukoil station at Eighth Avenue and 13th Street in Greenwich Village, took another plastic number last week, turned it over and scribbled “4” on it with a black magic marker. The result was an obviously homemade “$4.47,” but it would have to do until he received the extra 4s he ordered months ago.

“Typically, we have a lot of 9s and 1s, and we had a shortage of 3s before we got a lot of 3s in,” Mr. Nair said.

The missing digits are an unanticipated barometer of how frequently prices are changing. The average price of regular gasoline in New York City has risen by 35 percent this year, forcing station managers to change their price displays almost every time they get a delivery, which can be daily at some stations.