Your current assignment bores you or you need a couple of minutes off with a puzzle that is both rewarding and useful? Spend it on Project Euler:
Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.
The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context.
Dark Views 
Couple of minutes?
Man you must be smart đŸ˜¦
No, experienced đŸ™‚ I’ve already seen many of the problems in one way or the other over the years. That helps. But it’s also a nice playground to get new ideas, spend a some quality time, filling gaps, dusting off knowledge.
Project Euler is pretty fun, I got totally addicted lately, but it takes me ages.
But maybe one day in the very distant future I will get to be experienced too ^_^