I loved loved loved the part about the curvature per mile. Last weekend I was cutting the top of a door on a diagonal that had to match the sloped roof-line of

I loved loved loved the part about the curvature per mile. Last weekend I was cutting the top of a door on a diagonal that had to match the sloped roof-line of a new doorway I'm putting in on my second floor. When I calculated the slope, I incorrectly rounded up to too few decimal points ..such that over the length of the door (~ 31 inches) the error caused the slope to be off about 1/2 inch -- which, had I cut the door, would have looked horrible. This problem really perplexed me (because I'm an idiot!) ...until I saw the answer staring me right in the face on my calculator - the many values to the right of the decimal. Of course, leaving those there fixed the issue, and I got a nice accurate slope over the width of the door :)