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<\/div>Eerie events often have mundane explanations<\/p>\n
Luciano De Polo Stokkete\/Alamy<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
I had a strange experience in a cafe recently. When paying for coffee, I asked to use the toilet. After I tapped my PIN into the card reader, the barista handed me a slip of paper that was blank apart from a single number \u2013 the same one I had just tapped into the keypad! It turned out that this was also the entry code for the bathroom door.<\/p>\n
Was this evidence of a shadowy plot by the agents of Big Caffeine? No, it was just a fluke, but the event got me thinking about coincidences more generally. Occasionally, we are faced with events that seem so improbable<\/a> we can\u2019t help but feel the universe is sending us a message. As a mathematician, I know that coincidences are often far more likely to occur than we think \u2013 and this fact can have serious consequences everywhere from the science lab to lottery kiosks and the law courts.<\/p>\n My coffee shop experience is a good place to start because we can calculate the exact probability of it happening by chance. There are 10,000 possible four-digit numbers, meaning a 1 in 10,000 probability that the door code matches my PIN. Unlikely, yes, but let us put it in context. The cafe was in York, UK \u2013 a\u2026<\/p>\n<\/p><\/div>\n