Sam Hernandez said he figured he won about $10,000 when the Wheel of Fortune slot machine he was playing at a Casino started to light up and ring.

But that Friday held a pleasant April Fools' Day surprise, Hernandez, 74, had actually won a $522,415 Jackpot prize with his $10 spin on the 25-cent-per-spin machine.

"I still don't believe it," he said Tuesday.

Neither did his wife, Sue, who was at the casino with her husband and thought he was trying to pull an April Fools' Day prank on her when he told her what he had won.

"I thought he was joking me when he came to get me," she said.

The Hernandezes say they visit the casino about once a week, and usually play the slots just for fun, never hoping to actually win big money.

They said they're going to give all the prize money -- which will be awarded in payments over 20 years -- to their four daughters who grew up in Lodi but now live in Stockton, Merced, Elk Grove and Monterey.

Retired almond farmers who moved to Lodi from Stockton about 25 years ago, the couple say they live comfortably enough now that they don't need the money themselves and decided their daughters should get it.

"Eventually they'll get it anyway," Sue joked.

After her husband had made the winning spin, Sue said casino employees cordoned off the winning machine and the one next to it. The Hernandezes then had to wait five hours for the owners of the company that made the slot machine to travel to confirm the winning payoff.