Math Mistake (sort of) – the problem with negatives


It has been a while since we’ve seen a math mistake in the news, but a recent search turned up an old one that I’d never seen (Thanks TwoPi for pointing it out!)  And the funny thing is, it’s not actually a mistake at all – the math is correct.  And that’s the problem.

Back in November of 2007, the National Lottery in the United Kingdom had a new scratchoff ticket for their “Cool Cash” Lotto.  The idea behind the game was the a person would scratch to reveal a specific temperature — say, 15º — and would then scratch to reveal  three more temperatures.  If any of these three numbers was lower than the Chosen Special one (15º in this example), then the person won a prize.  Hooray!

But this was in the UK, which uses Celsius, and negative temperatures are pretty common in the winter.  So the target temperature might be something like –7º, and the three additional temperatures might be –6º, –5º, and –4º.  From a mathematically correct point of view,  that’s not a winning ticket because all the numbers are above –7º.  But people who focused on the numberals 6, 5, and 4, all of which are less than 7, thought they’d won.

It took but a day for this to become a problem, and after no small amount of confusion on the part of customers and shopkeepers, the tickets were pulled.  They had lasted less than a week.  Lottery we hardly knew ye.

For more details, including a video, see the article in the Manchester Evening News:


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