When a Six is Not a Zero

I've always had bad handwriting, but usually I'm the only one who pays the price.  However, check out this story that just played out much to my chagrin:
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A student (AA), who usually does well in class, came by to take a look at her recent test on rotational motion (grades were posted online but I hadn't returned the tests themselves as some kids still need to take it).  A little testy about her not waiting until I return them to the entire class, I reluctantly agree to let her take a look ("I thought I did well and I just want to see where I went wrong." - how do you say "wait another week until everyone has finished taking it" to that?)

As I dig up the various sections of her test, I start lecturing her on playing the long game rather than the short game: "It's just one test, maybe you had a bad day".  Then I find her open response section: a B+ on a test that had a C average. "Ouch - you must have really bombed the multiple choice section" I say helpfully as I hand that over to her.  Now she's visibly agitated as something must have really gone wrong; her confidence is really shaken as she worries about what shenanigans happened on the other section.  I unearth her multiple choice section and see another B+.  Unable to contain myself I start lecturing her on the dangers of perfectionism and maybe even point a finger at her while saying "What? You did great on this hard test - what are you worried about?"

She looks confused for a moment and then looks at me and calmly says "If I have a B+ then why does it say I have a C- on Eschool?"

As the tower of righteousness inside of me crumbles into sheepish embarrassment, I look at my grade book for the first time and see that a 16 out of 18 really (really!) looks like a 10 out of 18 when I recorded her multiple choice grade in my chicken-scratch handwriting.  I show her the grade without making any eye contact and as I hope to just disappear somehow when she says "How come you didn't double check my grade when you know I normally do better?"

"Everyone has a bad day every now and then, don't they?" I stammer and melt into a puddle...