Gisele Geddings retired to Mount Pleasant after 32 years as a statistician for the Census Bureau, so she knows numbers, but astronomically long odds didn’t keep her from buying Powerball tickets Tuesday at the Scotchman convenience store.

“It’s about wanting the big jackpot,” she said. “It’s exciting, to get up in the morning and check the lottery.”

Tonight’s Powerball drawing — worth an estimated $360 million — is already promising one of the 10 largest multi-state lottery jackpots of all time, and studies have shown that it’s likely to attract people who don’t usually play daily number games or buy scratch-off tickets.

In fact, an S.C. Education Lottery study found that college graduates and people earning more than $80,000 are disproportionately likely to buy Powerball tickets, just as they are less likely to buy the lottery games favored by those with less education and lower incomes.

Professor Doug Walker teaches a course on the economics of gambling at College of Charleston, and has written the forthcoming book “Casinonomics.” He knows lottery games offer worse odds than the worst casino games, but Walker concedes that he plays the Powerball now and then.

“If it gets to $500 million, I’ll buy a couple of tickets,” he said. “It’s not a bad thing if it’s people spending a few bucks for entertainment.”

Of course, lots of people who buy lottery tickets spend more than a few bucks, and studies have shown that they are typically people who can least afford to gamble.

At the Food Mart No. 1 gas station and convenience store on Savannah Highway in West Ashley, some people were buying Powerball tickets Tuesday, but many more were buying scratch-off and daily-number tickets, often in large quantities.

One woman plunked down $120 for scratch-off tickets, as the card-verifying machine behind the counter kept chiming “Congratulations! You’re a winner!” while checking the tickets she had just turned in.

Food Mart No. 1 sells more lottery tickets than any other business in South Carolina, and has done so for at least five years running, recording more than $3 million in sales last year.

Behind the counter, Mehul Patel said he expects Powerball ticket sales to pick up today because the drawing will be tonight.

Despite the huge prize, which stood at $350 million Tuesday morning and kept climbing as more tickets were sold, Patel said he hadn’t seen a surge in demand.

“$350 million is not enough to get people excited,” he said.

It’s a sociological puzzle that a $350 million prize would not be enough to prompt a line, but a larger prize would.

“You have basically a zero chance of winning either way,” Walker said.

Indeed, the odds of winning the grand Powerball prize are 1 in 175,223,510. And yet someone eventually will win.

Maybe it will be a group of factory workers, like the ones in Iowa who shared a $241 million jackpot last June, or perhaps just one person, like the New Jersey man who hit a $338 million jackpot this year, resulting in news stories about the warrant for his arrest for failure to pay child support.

For frequent lottery players, no half-billion-dollar prize is needed to prompt a purchase. The chance of beating long odds and winning up to $20,000 on a $2 scratch-off card does the trick for many.

Through the end of April, the S.C. Education Lottery got 67 percent of its revenue from scratch-off games. The prize may be just getting back the amount paid for the ticket, but that’s enough to trigger the “Congratulations!” message on the card verifier.

“I just trust that I’ll hit one,” said Karen Speed of Charleston, who left the Food Mart No. 1 store Tuesday with a $10 scratch-off game and a Powerball ticket.

At a BP gas station and convenience store in downtown Charleston, near the Medical University of South Carolina, MUSC employee Lenaire Bryan was buying Pick 3 and scratch-off tickets Monday, some of the lottery games favored by frequent players.

“With the Powerball, it’s one in a million,” he said, drastically understating the odds. “With the scratch-off the odds are better.”

For the occasional Powerball players, though, it’s not the odds but the chance to risk two bucks on a chance at winning the kind of jackpot that would allow them to quit their job and buy an island, or whatever else they want.

“When it gets to $500 million, there will be lines,” Patel said.

Reach David Slade at 937-5552 or Twitter @DSlade News.