Is 「３人いるだと」 grammatical?


> ３人いるだと！？

Can you say ３人いるだ as a statement? If だと is simply だ + と, I would expect
３人いるんだと. Is だと considered a particle in its own right, with different rules
than だ?

![dato](https://i.stack.imgur.com/RoYLc.png)

Transcription of the contents of the picture:

> A: [何]{なに}がどうなってる!!  
>      17[区]{く}にも[傷の男]{スカー}!?  
>       じゃあ 3区のはなんだ!?  
>  B: ダグラス大佐！  
>       8区にも出ました！  
>  C: ……3人いるだと!?




`だと！？` at the end of a sentence, e.g.
[`何だと！？`](http://eow.alc.co.jp/search?q=%E4%BD%95%E3%81%A0%E3%81%A8&pg=1) "say
what!?" can indicate shock or disbelief, e.g. "you say there are three people
there!?"

**Edit:** The `だと` seems to have come from `だって`. According to Daijisen's
[last
definition](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%81%A0%E3%81%A3%E3%81%A6&dtype=0&dname=0na&stype=0&index=11523000&pagenum=1):

> ［終助］《係助詞「だって」の文末用法から》引用句に付く。相手の言葉に対して、非難・驚きの気持ちを込めて強調する意を表す。
>
> [final auxiliary] 《from the binding particle `だって`'s end-of-sentence rules
> of use》 Attaches to a quotation. Indicates additional emphasis of criticism
> or surprise in regards to the other person's speech/words.




`だと！？` at the end of a sentence, e.g.
[`何だと！？`](http://eow.alc.co.jp/search?q=%E4%BD%95%E3%81%A0%E3%81%A8&pg=1) "say
what!?" can indicate shock or disbelief, e.g. "you say there are three people
there!?"

**Edit:** The `だと` seems to have come from `だって`. According to Daijisen's
[last
definition](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%81%A0%E3%81%A3%E3%81%A6&dtype=0&dname=0na&stype=0&index=11523000&pagenum=1):

> ［終助］《係助詞「だって」の文末用法から》引用句に付く。相手の言葉に対して、非難・驚きの気持ちを込めて強調する意を表す。
>
> [final auxiliary] 《from the binding particle `だって`'s end-of-sentence rules
> of use》 Attaches to a quotation. Indicates additional emphasis of criticism
> or surprise in regards to the other person's speech/words.

