Ruby solutions to Project Euler coding challenges (http://projecteuler.net/).
These are my answers to Project Euler, an online series of progressively more difficult math problems. The programs should meet the "one-minute rule", as described on the 'About' page:
"Each problem has been designed according to a "one-minute rule", which means that although it may take several hours to design a successful algorithm with more difficult problems, an efficient implementation will allow a solution to be obtained on a modestly powered computer in less than one minute."