[mudita]

While some problems are actually solvable with just pencil and paper, this is not a requirement and the intention of the project is that problems will be solved with a combination of insight and coding.

From the Project Euler website:

"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."