From time to time you come across some interesting code or programming challenges,
such as the ones in Project Euler, some job interview challenges like greplin, or any of the other script challenges that are posted here.
All these require some fast, agile programming language with some kind of quick way to see the results, preferably command line. There's no need to worry about readability of the code or such.
You just need an answer, and fast.
What is a good language to solve these challenges? What is the best hands-on method for solving, if you have to choose a language and learn it from the start?
Project Euler tells you that lots of languages are suitable. Those problems are solved in every language from Perl to C#.
The language you should use for challenges is either the one you know best or the one you're trying to learn right now.