Have you ever seen a sign at a grocery store that says "ten items or less"? Professor English, don't call the manager yet, because it's not that simple. There is no hard rule about when to use less and more.
There are tons of exceptions to the rule that "fewer" refers to numbers and "less" to amounts.
If we are talking about things we count, we should use the word "less" and if we are talking about things we measure, we should use the word "less"
We say: under this rule.
“There are fewer security guards working today than yesterday, and they are less enthusiastic.”
Security guards are counted but we measure enthusiasm.
Does that make sense? Good. It doesn't apply to many common usages.
When talking about money, distance, weight, time, and statistics, we don't usually use the word "fewer". In these cases, we usually use.
For example, we talk about being broke.
“I have to rob the bank! I have less than a thousand dollars in savings!”
It wouldn't be wrong to say "I have less than a thousand dollars in savings", but it has a different meaning.
If you want to talk about a unit of money, you could use the word "fewer".
“After the explosion, I picked up ten 100-dollar bills from the vault floor. George snagged fewer than six.”
The basic idea is the same. For example:
“The cops will be here in less than five minutes!”
If you want to draw attention to the units of time as opposed to the general idea of time, you can use.
“Look at your watch! We have fewer than five minutes until the police arrive!”
The rule applies to distance.
“The police station is less than five miles from the bank!”
And weight.
“The last time I went to the joint, I weighed less than 200 pounds.”
When talking statistics, we use the wordless instead of the wordfewer. We say that.
“Less than 10,000 inmates are currently being held in federal prison for bank robbery.”
It is total anarchy, really.
There are phrases we use all the time that are not in line with the guidelines. One less thing to worry about is an essay of 800 words or less.
There is a sign at the supermarket that says 10 items or less. The sign is correct because it is the way it is used and it was never wrong in the first place.
It has been used by writers for over a thousand years. It has 888-282-0465 888-282-0465 888-282-0465 888-282-0465 888-282-0465 888-282-0465 888-282-0465 since it was wrongly declared a rule.
Robert Baker is thought to be the culprit. Less is most commonly used in speaking of a number, where I think Fewer would do better.
Baker doesn't say this is a rule. He says "I should think" and "Seems to me", but Baker is only saying his preference. Our own desire to seem smarter than the person who writes the signs at the supermarket resulted in generations of English teachers recasting Baker's preference as a rule.
It is up to you when to refer to a number. There is nothing wrong with a sign that says 10 items or less, and you can tell your English teacher about it.