The BBC’s magazine monitor has a riddle every Monday, set by a guy from the Puzzletome website. There are always less than obvious solutions to these riddles which keeps people occupied, rather than doing work I suspect.

It reminds me of the time I wrote a computer program to solve n-order simultaneous differential equations. Why would I write it? Well, it’s all to do with curve fitting. Pick a set of n points, and try to find the equation that fits all of these points. Using differential equations you can find such an fit.

It then got me thinking (this is back in, I dunno, one holiday when I was in my sixth form at school) that there are a lot of riddles which are of the ‘next in series’ form. Find the next number in the series 1, 2, 4, 7 etc. Trouble is, once you know that you can find an equation that fits n points or values, you know that there will be one that fits n+1 points or values. Furthermore, you know that any additional point can be made to fit. So, when people ask you the next in the series, you can rightfully state anything you like because there will always be an equation to fit the entire series.

So it’s the same with these riddles. And anything else you need to find an algorithmic solution to. Make up anything you like. Just make sure you don’t have to prove it.