We aren't in the UK. The school year ends this week and portfolios/reports came home today. There's a page in DS's portfolio which is a timed maths test - basic facts of different levels. He has done pretty well on the test, maths is his strongest subject, but only closer inspection I have counted 4 questions that the teacher marked wrong that he has actually got right! A couple of them are obvious teacher errors (subtractions) and a couple of them are more tricky - eg write 60% as a fraction and DS has written 3/5 (she corrected this to 6/10, so maybe she wanted the working out, but his answer isn't wrong).
Would you bring this up with the teacher and be a pedantic pain in the arse? Would you ignore it as we are close to the end of the year and he'll have a different teacher next year? The same thing happened in the mid year portfolio, although it was only one question, albeit a very detailed fraction question that DS had got wrong but the teacher had corrected wrongly as well. I don't know how much this test has affected his results for the year - I'm guessing it won't change anything significantly.