This one gets me going. It's bad enough when applied,say, to the number of workers laid off, as in " the workforce was decimated" as a general indication of wholesale redundancies.
The worst is when it's applied to places as in " the countryside was decimated by Hurricane F*ckwit".
A near relation is the "amount" of people rather than "number".
Sorry, I've had day of marking essays so my teeth are a bit pointy.