I know what you are talking about. I was confused in the same way. First is fine with fewer hence the second should be fewer as well since number can be counted.

I use this rule to resolve such cases- Consider the word to which fewer/less applies. 1 species of frog, 2 species of frog.. makes sense right? whereas 1 number of species, 2 numbers of species and so on, does not make sense in this case. hence number is not countable. Number is an attribute that has a numeric value. To be more clear, number can be counted but it is not a countable noun.
Consider this:
The population density of US is less than that of Bangladesh.
The population density of US is fewer than that of Bangladesh.
Density can be counted but it is not a countable noun. 1 density, 2 density does not make sense.

yeah...that makes sense...

The rule is less modifies a singular noun. Fewer modifies a plural noun. Whenever you see a question that ask you to determine which word to use, identify the noun.

In your first sentence species was the noun that fewer was modifying.

In your second sentence the noun was "the number" therefore less would be used. Don't fall for the trap that they use where they make the prepositional phrase plural. Whenever you see "of" that and what follows it is a part of the prepositional phrase, so go by the noun that is in front of the prepositional phrase to determine if it is singular or plural. Hope that helps.

osirus0830 wrote:The rule is less modifies a singular noun. Fewer modifies a plural noun. Whenever you see a question that ask you to determine which word to use, identify the noun.

In your first sentence species was the noun that fewer was modifying.

In your second sentence the noun was "the number" therefore less would be used. Don't fall for the trap that they use where they make the prepositional phrase plural. Whenever you see "of" that and what follows it is a part of the prepositional phrase, so go by the noun that is in front of the prepositional phrase to determine if it is singular or plural. Hope that helps.

Right on the money. Thanks for explaining this rule. I was going to mention it but you already did.

Fewer than 1000 species

The # of is singular . hence , the number of ...is less than 1000...

hope this helps

nikhilgirdhar wrote:There are fewer/less fewer than 1,000 species of frog left in the amazon river basin.

The number of species of frog left in the Amazon river basin is fewer/less less than 1,000.

Please choose the appropriate word and explain why?

nikhilgirdhar wrote:There are fewer/less fewer than 1,000 species of frog left in the amazon river basin.

The number of species of frog left in the Amazon river basin is fewer/less less than 1,000.

Please choose the appropriate word and explain why?

A fewer and B less

The words fewer and less are commonly confused in English, or rather, less is used while fewer tends to fall by the wayside. You'll be less confused and make fewer mistakes after reading through this lesson.


Fewer

Fewer is used with countable nouns: people, animals, chairs, shoes.

You know fewer people than I do.

There should be fewer books on the table.

I have fewer ideas than everyone else.

Fewer of us show up each year.


Less

Less is used for uncountable, usually abstract nouns: money, happiness, snow, idealism.

I hope less snow falls this year.

We need more money and less debt.

I have less computer savvy than you.

You should spend less of your time complaining.

Less is also used with adjectives and adverbs:

I'm less happy than I used to be.

He runs less quickly than you.