For anyone who wonders about the applicability of advanced math to everyday life:
When you think about RAID-5 at a superficial level, it kinda makes sense - 'sure, you can take a 1/n capacity hit to ensure that you still have all your data if one drive dies, why not?'
Then you think about it a bit harder and think waiiiiiiiit, how does that work EXACTLY?
Then you go look up how RAID-6 works and bless the mathematics departments...
(note to mathematicians: this may well not be 'advanced' to you. It sure is to the rest of us, though.)