If you’re like me and love coding, but your daily work can go long stretches without coding, you’ll like Project Euler, where you can solve math problems using any programming language you like (as a long-time user, I use Python, since I use R more often when modeling data).
The project now has nearly 900 problems, with a new one added about once a week. The problems vary in difficulty, but each can be solved in less than a minute of CPU time using an efficient algorithm on an average computer.
Also, my recommendation engine says that if you like Project Euler, you might also like this SQL Murder Mystery I just discovered. This one is not really that difficult, but it does require you to pay close attention to the clues and prompts.