<an> extra / further / additional

Hello,

I'm wondering if the following sentences are OK:

(1) We're planning to open an extra 5 stores.
(2) We're planning to open an additional 5 stores.
(3) We're planning to open a further 5 stores.

(4) We're planning to open 5 extra stores
(5) We're planning to open 5 addtional stores.
(6) We're planning to open 5 further stores.

Thank you.

They all seem fine to me (apart from addtional in #5;-)). I prefer 'further' and 'additional' to 'extra'.

Thank you, fivejedjohn. But..... considering extra / further / additional are adjectives, what does the article in 1-3 refer to?

Quote:

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Originally Posted by Verona_82

Thank you, fivejedjohn. But..... considering extra / further / additional are adjectives, what does the article in 1-3 refer to?

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Hmm. That's caught me. Back soon.

Clive seems to have the answer: Use of "an" before a plural, modified noun