YOU SAID:

I have twelve kids in my basement

INTO JAPANESE

地下室に12人の子供がいます

BACK INTO ENGLISH

I have 12 children in the basement

INTO JAPANESE

地下に12人の子供がいます

BACK INTO ENGLISH

There are 12 children in the basement

INTO JAPANESE

地下には12人の子供がいます

BACK INTO ENGLISH

There are 12 children in the basement