Blog posts with problems to get your brain going! You get a new problem every fortnight and the solutions are published later.

If you want the problems delivered to your inbox be sure to subscribe to the Problems newsletter.

The next problem is scheduled for Sunday, 7th of February.

You may notice some problems are missing... I'm still migrating articles from my old blog.


There is a key hidden in one of three boxes and each box has a coin on top of it. Can you use the coins to let your friend know where the key is hiding?


I bet you have seen one of those Facebook publications where you have a grid and you have to count the number of squares the grid contains, and then you jump to the comment section and virtually no one agrees on what the correct answer should be... Let's settle this once and for all!