Title seems wrong. I think this was intended to be "12 Kb executable runs natively on 7 operating systems". The HN suggestion of copying the article title would be: "How Fat Does a Fat Binary Need To Be?"
I believe HN filters out numbers at the start of the title.
When HN mangles your title, you can restore it to sanity by editing the item: it only changes it on creation, not edition.
I wonder what's the reasoning behind that, it sounds pretty braindead.
Filtering "listicles", articles with titles like "6 Secrets to Achieving Work-Life Balance", "23 Amazing Moments From The Harry Potter Movies", "5 Steps to Booking a Cheap Flight Online" and similar.
But what if number 4 shocks you? /s
Yes, but the original title shouldn't have been rewritten in the first place since it was neither misleading nor linkbait (from https://news.ycombinator.com/newsguidelines.html: "Please use the original title, unless it is misleading or linkbait; don't editorialize."). I've fixed it now.