Russians Engineer a Brilliant Slot Machine Cheat—And Casinos Have No Fix

In early June 2014, accountants at the Lumiere Place Casino in St. Louis noticed that several of their slot machines had—just for a couple of days—gone haywire. The government-approved software that powers such machines gives the house a fixed mathematical edge, so that casinos can be certain of how much they’ll earn over the long haul—say, 7.129 cents for every dollar played. But on June 2 and 3, a number of Lumiere’s machines had spit out far more money than they’d consumed, despite not awarding any major jackpots, an aberration known in industry parlance as a negative hold.