Camelot, which runs the lottery in the UK, has been forced to scrap one of its new games because punters couldn't understand it.
It's hardly Mastermind, but the Cool Cash game - launched on Monday - was taken out of shops yesterday after some players failed to grasp whether or not they had won.
To qualify for a prize, users had to scratch away a window to reveal a temperature lower than the figure displayed on the card they'd bought. As the game had a winter theme, the temperature was usually below freezing.
However, the concept of comparing negative numbers proved too difficult for many and Camelot received dozens of complaints on the first day from players who could not understand how, for example, -5 is higher than -6.
Tina Farrell, from Levenshulme (near Manchester), called Camelot after failing to win with several cards: "I phoned Camelot and they fobbed me off with some story that -6 is higher, not lower, than -8 but I'm not having it."
And who said that standards of education were slipping? Fantastic!