I'm sort of with Youngest Tall Boy... why would they have a stupid rule like that? If you KNEW you did it wrong, why couldn't you fix it? Not uncommon for gifties to rebel against authority in this situation (I suspect that 40 years ago I would have done the same thing). I assume this was some kind of speed math exercise or something.
This touches on whether it is best to teach our kids to go along to get along. It makes life easier for everyone if they do, but I understand when my kids don't want to do that. I do advise them to "keep their powder dry" -- don't rebel against EVERY stupid rule. Save it for situations that matter, and this probably isn't one of them. I think this visualization (we had to talk about muskets and shooting bears vs. shooting at tine cans :)) did help them.
My D15 is having her own little rebellion at the moment. Her gym teacher offered 10 points of extra credit for any kid who makes and brings in a "mix tape" on CD (music they can listen to in the gym and weight room). She thinks this is copyright infringement (guess those lectures on not swapping music sank in!), and she decided to write a paper on copyright infringement and turn it in to him instead. No idea how he will take it... I guess we will see!