Interesting Problems for NonMath Majors Sometime in the upcoming future, I will be doing a presentation as a college alumni to a bunch of undergrads from an organization I was in college. I did a dual major in mathematics and computer science, however the audience that I am presenting to are not necessarily people who enjoy math. So, to get their attention, I was thinking about presenting an interesting problem in math, for example, the birthday problem, to get their attention and have them enjoy the field of math a little.
I feel a question in the field of probability would interest them the most (due to its instinctiveness) , although that's just a personal opinion. The audience studies a variety of majors, from sciences to engineers to literature and the arts. 
So here's my question, besides the birthday problem, are there any other interesting problems that would be easy to understand for people who have limited knowledge of calculus and would, hopefully see math as an interesting subject and get their attention? (Doesn't have to be in the field of probability.)

I think geometry is the area the most attractive that a "non-mathematician" can enjoy, and I believe that's the idea Serge Lang has when he prepared his encounters with high school students and in his public dialogues, I refer her to this tow reports of These events :
The Beauty of Doing Mathematics : Three Public Dialogues
Math! : Encounters with High School Students
I hope you can access to these tow books because, I think they might provide something helpful for you.
