Golf All The Eulers!

A project for golfing every Project Euler problem.

Rules

No hardcoding of the answer. Use your common sense.
Output your answer to STDOUT.
All answers must work "out-of-the-box" - i.e. all files have to be complete by itself, without any changes to the file.
Your program should work with the standard compiler for the language (aka gcc, g++, python) by itself, without any third-party add-ons. If there is no one official compiler/interpreter for a language, please specify one in the README of the respective question.

Go to the respective folder.
Post your program with the following name: {name of lang}.{extension}. For example, a program made in C# would be called csharp.cs.