Grammar Friday - Fewer vs Less

Here's your quiz question for the day:

You should invite (less, fewer) girls to the party.

In this sentence, which is correct? Less or fewer?

Does it help to think about how they do it in the grocery store? Surely we can count on the people ordering/designing/making the signs to know what's right. Right?

Ummm ...

  Actually, no, you can't count on them to know what they're doing. I see and hear less used incorrectly all the time. And I personally think the people who made that mistake with these signs--and have perpetuated the error--are training people to think less is the correct word. You hear it enough times incorrectly, your brain will reject something different, even if the different is the right way to use the word.

And who better than Delta Airlines to provide me with a prime example in a frequent flyer email I received while writing this post?

Please note that when I was in Ireland in April, their signs said fewer. The Irish get it.

So the rule? It's pretty simple.

Less is used for quantities

The amount of money in my savings account is less than it was last month.

Fewer is used for individual units, numbers

You will need to make fewer mistakes in your report.

Hint:    Less = singular
           Fewer = plural