A few days ago, Allison posted a problem you could really sink your teeth into and enjoy the puzzle of it all. It reminded me that it's been a while since I did this sort of brain challenge type problem just for the heck of it. Many years ago, I came across this problem:
Consider a square cake that's frosted on the top and sides. How do you cut it into 5 pieces so that everyone gets the same amount of cake AND the same amount of frosting? You must serve the whole cake. (be able to prove why it works) (added bonus: what if it's a rectangular cake?)
Now as a selfish person, I'm wondering if anyone has links to other cool such problems that make you think and tinker for a longer while than usual. Share! Share!