## Monday 13 November 2017

### 9 43 25 36

I'm just a little bit addicted to Quora. A while back I signed up for a Quora "feed" which delivers a pot pourri of Q&A a couple of times a day. Like much of social media, the material is crowd-sourced: the more 'like'able posts are pushed to the top so are more likely to be read and so they are further buoyed up. Harry Potterism at work. It is a global community but some people seem to spend their entire lives there; endlessly answering similar questions that fall in their area of expertise.

Many youngsters seem to use the resource to get someone else to do their homework. A recent example being "which of these numbers 9 43 25 36 is the odd one out". It's essentially the IQ-test standard Q of "What is the next number in this series?" which separates the innumerate from those who can recognise patterns.  Those who know numbers, and have done a few IQ tests will instantly see that three of the numbers are perfect squares and so 43 is the rogue. But people who are open to other possibilities note other dimensions of difference.  Prof Douglas Eckberg noted that 9 is the only single digit number, 36 the only even number and 43 the only prime . . . "Therefore, 25 is the only number without a unique characteristic." and then thought about it to add that 25 is also unique if you can think of an obscure enough way of looking at it. This puts "we hold these truths to be self-evident" under the skeptical spotlight: everyone will have a different answer depending on their age and cultural background. This was exposed ironically by another academic Robert-Jan Kooman "25 does not belong. I am 43 years old, my wife is 36 and our daughter is 9. There is no one in our family that is 25 years old, so that number certainly is the odd one out."  HoHo. Giorgios Skoufos steps further outside the box: "nine, forty-three, twenty-five whereas thirty-six. But there is a more general message here about parking your own certainties - especially when in dialog with others; especially if they are different. Different isn't wrong, it is interesting!