I took a test for a scholarship that had mathematical "riddles" just like Micromass' challenges. It was multiple choice and I guessed for some, but others I was able to do or at least use process of elimination. I didn't think I did that well, but I advanced to the second round. Could I have some strategies for doing these problems? Problems were in the form: There exists (some amount) of numbers that satisfy (some condition). What is the sum of the numbers? How many ways can (this set) be arranged so (this condition) is satisfied? And other things like that. Thanks!