How to not yell at simple things?

I yell really loudly, sometimes wake people up, and it always embarasses me afterwards. I yell because I get frustrated that something isn't the way it should be, like recently, I did two or three problems that were wrong, even though I was doing them the way I was taught to do them. Turns out the answer was I think I wasn't reducing the fractions completely. So how do I not blow up at the earliest and easiest opportunity to do so?

when you feel those strong feelings coming, take a breath.