Hello native English speakers.

Which noun phrases are grammatically correct?

1a. two hundred of apples.=

1b. two hundred apples.
( 1a = 1b? Both are grammatically correct?)

2. a million of thanks.=a million thanks.
3. several hundred of us.
4. a few hundred men.
5. two dozen of the big doughnuts.=
two dozen the big doughnuts.
6. thousands of birds.
7. many thousands of birds.
8. some hundreds of these birds.
9. hundreds of thousands of feet.
10. many/some dozens of big apples.
11. several hundred tickets.
12a. several hundred of these books.=
12b. several hundred these books.
13. a few hundreds of houses.
14. a thickness of many hundred or even some thousands of feet.

Question

Hello native English speakers.

Which noun phrases are grammatically correct?

1a.  two hundred of  apples.=

1b.  two hundred apples.
( 1a = 1b?  Both are grammatically correct?)

2.  a million of thanks.=a million thanks. 
3.  several hundred of us.
4.  a few hundred men.
5. two dozen of the big doughnuts.=
two dozen the big doughnuts.
6. thousands of birds.
7. many thousands of birds.
8.  some hundreds of these birds.
9.  hundreds of thousands of feet.
10. many/some dozens of big apples.
11. several hundred tickets.
12a. several hundred of these books.=
12b. several hundred these books.
13. a few hundreds of houses.
14. a thickness of many hundred or even some thousands of feet.

Answer

If the quantity [number] word  eg  dozen, hundred, thousand  is singular you don't use 'of' before the things concerned
eg  two dozen large doughnuts, two hundred apples, a thousand birds, several hundred tickets

If the quantity number word is plural you add 'of' before the things you are referring to
eg.  hundreds of people, thousands of birds
This is usually less precise than when you say 'two hundred people',  'five thousand birds', etc.

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