Octal modes aren't necessary anymore, chmod has symbolic modes. And "man chmod" is there to help if you forget. I think this is solving the problem "I don't understand octal" more than helping with using chmod.
Its an alright resource for people learning chmod. Id also include all the r+w format too<p>Just wonder where defaulting to -R 777 is a good idea for people learning chmod? They might run and chmod the whole directory on their first attempt