From your post it sounds as though you are equating a "square" of chocolate with a "bar" of chocolate. Perhaps it is I who am wrong, but I have always understand "square" to be one of the bits that chocolate bars are divided into - that would be 12 or 16 (or so) "squares" in each "bar". Read the nutrition label; chocolate bars are often 100 grams. On the 90% bar I have in the pantry it says 1 serving is 40g (4 squares) & 12g total carbs. Therefore the whole bar would be 30g total carbs. I never eat more than 1 or 2 squares at a time.
I apologise if I misread your post.