I can't think of anything which comes to mind particularly but I'm sure I've messed up a lot of maths exams and when talking about it after someones said what they put and I've kicked myself.
I have however got to the end of maths exams and wrote random numbers in the answer boxes in the last 30 seconds, none of which have ever come right I don't think.
I completely forgot an entire topic that featured on a Geography GCSE exam. When I got to that section on the paper I scribbled some nonsense and induced a nosebleed all over those pages so they were illegible. Somehow I scraped a C grade but I now do feel very sorry for the poor examiner.
Oh, and knowing I was going to fail big time on my German oral exam I decided to learn only one phrase - 'I don't know'. Then problem was I learned it wrong and answered every question with 'I white know'. Doh!
this isn't really an accidental mistake. But once in a science GCSE (wasn't a fan of science tbh) anyway there was a question I didn't really understand, I was staring at it for a while in the end I wrote THIS QUESTION DOESN'T MAKE SENSE. that's how far I've got though hahaha
Thought it would be appropriate to point that out, given the thread topic.
Got beaten to my post.
And my addition is probably the making up of how Hitler became Chancellor of Germany last year in history - I knew he was popular so I wittered on about his popularity and that was the key to getting anywhere in life. Still got an A* my fave examiner to date probably.
Not strictly appropriate as it was during a medical interview, where I said that the exponential curve was quadratic... and then proceeded to defend myself by explaining I was actually rubbish at maths when I had noticed my mistake immediately after having said it was quadratic unsurprisingly I was rejected