The main thing I find myself explaining with percentages (IANA educator) is that 'grossing up' != adding the same percentage back, e.g. 80% * 1.2 != 100%, which looks pretty obvious like that, but it's a common mistake among adults talking about real life percentages like taxes.
Another common, and I suppose related, one (but that I don't bother correcting often) is 'percent' != 'percentage point'. Talk of 47% of something being '3% less than' half of it really winds me up - and it's stupidly common among journalists - but it's too common to bother pointing out IMO. Live and let get wrong.
Another common, and I suppose related, one (but that I don't bother correcting often) is 'percent' != 'percentage point'. Talk of 47% of something being '3% less than' half of it really winds me up - and it's stupidly common among journalists - but it's too common to bother pointing out IMO. Live and let get wrong.