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 late June.
You may notice some problems are missing... I'm still migrating articles from my old blog.
You are sunbathing when you decide to go and talk to some friends under a nearby sun umbrella, but first you want to get your feet wet in the water. What is the most efficient way to do this?