the SI people are right and everybody doing it otherwise is wrong; you should never use the "K", "M", etc unit prefixes to mean factor of 1024. sure, with small enough sizes you can usually ignore it. but scale it up and you quickly run into trouble
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Anyway, 
@whitequark✧✦Catherine✦✧ has the right of it. Use SI unit prefixes to mean SI unit multipliers, period. "kilo-" means "1000," period. "kibi" means "1024," period.
https://social.treehouse.systems/@whitequark/116145581473013061