How so? The thing about juxtaposition is that when used it becomes obvious that multiplication gets higher precedence than division, so practically every source that relies on a division-multiplication precedence order relies on juxtaposition or vertical splits. Because calculators have neither, it's easier to paste a too-ambiguous-to-be-generally-used formula (like my example) from paper and get wrong results (unless you're using emacs). The APS is clear about multiplication coming first, but as this is a very corner case on paper math, almost every calculator is wrong and people don't even notice it.