These programs were written on a 64-bit machine, and at this point in time
have no concern about being 32-bit or cross platform compatible.

To compile a solution:

gcc euler1.c -lm

Often times after solving a solution I will implement the discussed solution
just to see how it differsi with mine and to get a little bit of muscle 
memory in case I see the problem again in some other situation.

Problem 15: is simple (2n choose n) for an n by n grid