Amazing events have common explanations
Luciano De Polo Stokkete/Alamy
I recently had a strange experience in a coffee shop. When paying for the coffee, I asked to use the bathroom. After entering my PIN into the card reader, the bartender handed me a piece of paper that was blank except for a single number, which I had just typed into the keyboard! It also turned out to be the entry code for the bathroom door.
Was it evidence of a shady plot by Big Caffeine operatives? No, it was just a coincidence, but the incident got me thinking about coincidences in general. From time to time, we find ourselves faced with events that appear to be so it is likely we can’t help but feel like the universe is sending us a message. As a mathematician, I know that coincidence is much more likely to occur than you think, and this occurrence can have serious consequences everywhere from the science lab to lottery kiosks to courtrooms.
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 10,000 chance that the door code matches my PIN. Hardly, yes, but let’s put it in context. The cafe was located in York, UK…
