grammar - Function of Numbers in a Sentence

A question was recently posed about the sentence

"This is what 51,000 people looks like."

The question was, "Is this grammatical?"

It seems opinions vary on how to handle this sentence. I feel that 51,000 is an adjective describing people and so "looks" should be "look" as in "This is what 51,000 people look like."

These are my questions:

1) What function does 51,000 serve in the sentence?
2) How are numbers treated in general when they appear before nouns? I ask because I have heard people say "Here's 30 Dollars." Should it be "is" or "are?" Seems like people are referring to "30" and not "Dollars."
3) What function does "look" play in the above sentence?

4) Also, it seems that because 51,000 is written as a number (instead of fifty one thousand) people are treating it like a group whereas if it were written, I think it would be harder to do that. Does writing it as a number or as words change things?
5) Also, if the sentence were "Here is what 51,000 people looks like." would the word "here" change the sentence and how we parse the it?

Answer

1. Quantifiers generally act as determinatives, which define the nouns they modify. This is different from adjectives, which describe the nouns they modify. You can tell the difference because determinatives cannot be inflected for comparison, and they can't appear as predicate adjectives. You can say either

Purple people are here or People here are purple

but you can only say

51,000 people are here.

You can't say

People here are 51,000.

2. Whether you hand someone a twenty-dollar bill or a two ten-dollar bills, you say

Here is twenty dollars.

Because that's a single amount, no matter the denomination of the bills.

3. "Look" is a stative verb in your example. It means "appears."




4. I don't see how numerals or words affect the grammar. Whether you choose a singular or plural verb depends on whether you mean the group as a whole or as multiple individuals. If you say

51,000 people seems small for a protest rally

you mean that it's a small crowd.
If you say

51,000 people seem small

you mean that either they are all midgets or they are being viewed from afar.

5. "Here" is an adverb of place, telling us where they people appear as they do. Its presence or absence doesn't change the basic structure of the sentence.