> I'm thankful every day that throughout my education it was drilled into me never to circle my answer at the end of a math problem until I first re-read the problem and asked if my answer made any sense.

I had always done this, but I remember hitting a word problem in calculus where the calculation came back with something that made no intuitive sense. I remember staring at it and re-tracing each step before turning it in, certain that I had have made a mistake, but unable to find a problem. It turned out that nothing was wrong, the values just weren't real-world consistent.