YOU SAID:
I have 12 days to live
INTO JAPANESE
私は12日生きています
BACK INTO ENGLISH
I live 12 days
INTO JAPANESE
私は12日間住んでいます
BACK INTO ENGLISH
I live for 12 days
INTO JAPANESE
私は12日間住んでいます
BACK INTO ENGLISH
I live for 12 days
That didn't even make that much sense in English.