Is it better to say (about rates of production) '200 ton per hour' or '200 tonS per hour'? The number of tons can vary... I just come across both variants so often that it is difficult for me to differentiate between them. Seems both of them are used equally.
The same is with sums of money - for example, when you repeat them in words - do you say 'XX thousand dollar/pound' or '...dollarS/poundS'?