When calculating inflation, economists look at the cost of products in thousands of locations across the United States. In Lexington, though, the easiest way to see how prices are going might be to look at the famous Burger Shake sign on East New Circle Road.

As prices of everything from corn to clothing have soared this summer, the iconic local fast-food sign saw a change, too: The cost of a burger went from 84 cents to 99 cents this summer.

"All of our costs started going up like crazy," co-founder Joe Isaac said. "We couldn't hold the line anymore.

"We didn't want to make our product any smaller, so we raised the price to where we could afford it."

Because of increases in the price of bread, meat, transportation and just about "everything," he said, the price increased for the first time in three years.

Customers haven't complained, though. "Our customers are probably the most loyal that I know," said Isaac, 85, who founded the restaurant in 1957 with Dr. Samuel Isaacs. Their daughters, Sharyn Clements and Sammie Lou Lilly, respectively, now own the restaurant, which features an oddity of a name.

"The name of the company is I&I Inc., but we didn't have any more money after we put that sign up," Isaac said. "It cost a fortune." Ever since, it's just been called "Burger Shake," even though Isaac noted the sign makes both words plural: Burgers Shakes.

Besides the prices, the sign has changed somewhat over the years. The price was originally lit in neon, "but when the prices went up, it was so expensive to change the neon that we started using plastic letters."

He says they might look pretty cramped when the price eventually rises above a dollar.

"It doesn't look like there's that much more room over there," he said.