Alright, well seeing as my last challenge lasted a whole 30 minutes before Jimmy Snyder solved all my brain teasers, I dug deep to find more challenging ones. Please use and and the closing tag [/ color] to make your text unreadable to those who don't want to see the solution, thanks. If you recognize any of these puzzles from old threads please either ignore them or link to them and I may remove those puzzles from this thread to ensure that these are all new. Thanks. Good luck!! 1.Three distinct points with integer coordinates lie in the plane on a circle of radius r > 0. Show that two of these points are separated by a distance of at least r^(1/3). 2.What chemical compound is represented by the following: HIJKLMNO? 3. On his way to work each day, a man living on the fifteenth floor of an apartment building takes the elevator to the first floor from the fifteenth floor. On his return, he is forced to take it to the seventh floor and walk the remaining eight floors to his apartment. Why? 4.Three criminals just robbed a bank and go back to their hideout. They put the money behind a high tech security door. There are 3 locks on the door, each activated/deactivated by a button next to it. All locks are originally deactivated, and once a lock is activated it is impossible to tell whether it is activated or not. The three criminals want to work out a system so that any two of them can access the money but a single criminal cannot. The 2 criminals accessing the money must be assured that all locks are deactivated, otherwise an alarm will sound, and built-in lasers will shoot them. Also, each criminal may only give information about which locks he toggled to one other criminal. Figure out how their system will work. 5.Punctuate the following so it makes sense: Alice while Matthew had had had had had had had had had had had a better effect on the teacher.