If you don’t play, you can’t win the lottery, the ads say, but amazingly many winners are losing out by not claiming their prizes before they expire. In 2007, $628 million went unclaimed, according to unclaimedlotterys .com. And it’s not just chump change. A winning ticket for $51.7 million went unclaimed in Indiana, and there are quite a few other tickets in the multimillions no longer worth the paper on which they’re printed. Currently, unclaimed prizes for about half the United States are posted on that site.