Just got cussed out by a parent. Advice for dealing with difficult parents?

Details: <br><br>Teach 7th grade Math. Recently graded all 3rd 9 weeks assignments for my students. Parent asked "why does their grade say 0"? I was like "hold up, lets look at this together. Here is 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0". Proceed to get called a jerk and a smartass and for the parent to be visibly upset, all for simply answering their question. <br><br>Im new this year into a school and its my first year, never encountered anything like this before.