How should I deal with students copying down the problem incorrectly? I give quizzes in my recitation classes. I write down the problems on the board. My handwriting is okay but not great and most students can read what I'm writing but because of chalk marks, bad writing, bad vision or whatever some students copy down the problem incorrectly. Mostly the changes are trivial (I wrote a 2 and they wrote 12, but the computations are the same). Sometimes the way they copy down the problem significantly changes the problem. 

I don't want to penalize the student for misreading. But I don't want to be unfair if the problem is harder or easier for that student. 

How should I grade these problems?

EDIT: I have 80 students. I give 21 quizzes in a semester. That is 1680 quizzes in a semester. Maybe 1 or 2 of those are miscopied to the point of being different problems. I am not going to change how I give quizzes for such a tiny irrelevant fraction of quizzes.
My solution is rather boring and simple. What if, after writing the problems on the board, you read the problems outloud with and or to the students. Hearing the problems will reduce many mistakes due to mis-seeing what's on the board.

After reading with or to them you can then ask the students if anything is unclear on the board. They ask and you can clarify your handwriting.